Master the main chess lines with direct explanations, plans for White and Black, frequent mistakes and training with Stockfish 18.
1.e4 c5
The Sicilian Defense (1.e4 c5) is the most played answer to 1.e4 and the one that least resembles a defence: instead of mirroring White's move in the centre, Black trades a flank pawn for a central one and ends up with the c-file open for a rook. After 1.e4 c5 the position measures +0.30 for White — less than most closed openings concede — and the seven main families sit between +0.25 and +0.71, measured here with Stockfish 19.
See the full guide and plans1.e4 e6 2.d4 d5
The French Defence (1.e4 e6 2.d4 d5) hits White's centre on move two and accepts, in the same breath, the problem that follows it all game: the c8-bishop sits behind its own pawn chain. The position measures +0.46, the highest among the defences to 1.e4 in this batch, and White's third move changes a great deal — the Winawer and the Classical both measure +0.62, while the Tarrasch sits at +0.19.
See the full guide and plans1.e4 c6 2.d4 d5
The Caro-Kann (1.e4 c6 2.d4 d5) solves, with one modest pawn move, the problem the French Defense leaves open: Black contests the centre with ...d5 and still keeps the c8-bishop's diagonal clear. The price is time — ...c6 develops nothing — and after 2...d5 the position measures +0.31 for White. White's third move matters more than its reputation suggests: the Panov Attack measures +0.18 and the Classical +0.42.
See the full guide and plans1.e4 d5
The Scandinavian Defence trades the central pawn on move one and solves, at a stroke, the problem of anyone facing 1.e4 who does not want to memorise ten systems: after 1...d5 there is one structure to learn. The price shows in the measurement: the position measures +0.64, and the most popular version, with 3...Qa5, reaches +0.78. The queen comes out early, is attacked with gain of time, and White develops for free. What the defence gives back is predictability — and one line the engine approves of: the Icelandic Gambit, with 3.c4 c6, measures −0.62 in Black's favour.
See the full guide and plans1.e4 d6 2.d4 Nf6 3.Nc3 g6
The Pirc Defence lets White build the full centre with e4 and d4 and only then attacks it, with the bishop on g7 and the ...e5 and ...c5 breaks. It is a counter-attacking defence, and the measurement shows the cost of conceding the centre: after 3...g6 the position is +0.73, the same level as the Alekhine and the Modern. The more useful figure is another one. The Austrian Attack, 4.f4, reputed to be the refutation, measures +0.60, less than the starting position; the two lowest-rated White lines are the most modest ones, the 150 Attack (+0.30) and the fianchetto (+0.28).
See the full guide and plans1.e4 Nf6
The Alekhine Defence offers the knight as a target on the first move: 1...Nf6 invites White's pawn forward, on the theory that every advanced pawn becomes a target later. The measurement agrees with both sides. The position after 1...Nf6 is +0.73, and the line in which White advances most, the Four Pawns Attack, reaches +0.94. But the Modern Variation with ...Bg4 measures +1.09, the highest in the entry, and the attempts to chase the knight without a plan yield the least: the Chase Variation, with c4 and c5, measures +0.14.
See the full guide and plans1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5
The Italian Game (1.e4 e5 2.Nf3 Nc6 3.Bc4) is the oldest opening in the modern repertoire and still the first one nearly every player learns: the bishop eyes f7, the square Black's king still guards alone. After 3...Bc5 the position measures +0.24 for White, and what changed over the last twenty years is not the evaluation but the speed — the immediate d4 of the Giuoco Piano levels the score outright, while the slow 4.d3 keeps +0.16.
See the full guide and plans1.e4 e5 2.Nf3 Nc6 3.Bb5
The Ruy Lopez (1.e4 e5 2.Nf3 Nc6 3.Bb5) has been the most common opening in top-level chess for a century and a half, and the reason is structural: the b5-bishop attacks the defender of the e5-pawn rather than the pawn itself. The position measures +0.22 after 3.Bb5, and the spread between Black's replies is wide for such a studied opening — the Berlin measures +0.20 and the Steinitz Defence +0.70.
See the full guide and plans1.e4 e5 2.f4
The King's Gambit hands over a pawn on move two to open the f-file and build a centre with d4. It was the opening of the nineteenth century, and the measurement explains why it stopped being so: the position after 2.f4 measures −0.55, and none of the accepted lines improves on that — the Kieseritzky measures −0.64 and the Fischer Defence −0.80. The gambit does not lose by force: it loses because the correct defence is known. Where it still works is on the other side of the board, against players who decline it: 2...Bc5 measures +0.38 and the Falkbeer Countergambit +0.68. The f4 pawn is still a good practical bet and a bad objective one.
See the full guide and plans1.e4 e5 2.Nf3 Nc6 3.d4 exd4 4.Nxd4
The Scotch Game opens the centre on move three and solves, in one stroke, the problem faced by anyone who plays 1.e4 and does not want to study the Ruy Lopez: after 3.d4 exd4 4.Nxd4 there is no Berlin, no Marshall and no twenty moves of closed theory. The position measures +0.11 — less than the Spanish, and the number is honest about the trade. Kasparov used it in world championship matches for exactly that reason: against a well-prepared opponent, a mid-theory opening whose positions he knew was worth more than a main line both players knew.
See the full guide and plans1.e4 e5 2.Nf3 Nf6
The Petroff Defence answers attack with attack: instead of defending e5, Black hits e4. The position after 2...Nf6 measures +0.41, and the number misleads — it reflects the tabiya before any exchange. Once the main line unfolds, with 5.d4 d5 and full symmetry, the evaluation falls to exactly 0.00. That is why the Petroff has a reputation as a drawing defence at the top, and why Kramnik and Caruana used it to neutralise 1.e4 in games they could not lose. What this entry adds is what happens when the symmetry is broken in the wrong order — and that costs the queen on move four.
See the full guide and plans1.d4 d5 2.Bf4 Nf6 3.e3 c5 4.c3
The London System (1.d4 d5 2.Bf4 Nf6 3.e3 c5 4.c3) is the most popular White set-up in amateur chess this decade, and the reason is an honest one: it is played nearly the same way against everything, which saves dozens of hours of theory. What it does not do is grant an advantage. The position after 4.c3 measures exactly 0.00, and the sharper version, the Jobava, measures −0.04 — Black is already marginally better.
See the full guide and plans1.d4 d5 2.c4 e6 3.Nc3 Nf6
The Queen's Gambit Declined (1.d4 d5 2.c4 e6 3.Nc3 Nf6) is the classical answer to 1.d4 and the most resilient opening measured on this page: the position reads +0.22, and none of the seven main variations exceeds +0.32. Black shuts in their own c8-bishop on purpose, in exchange for a centre that does not give way — and the whole game turns on when, and whether, that bishop ever gets out.
See the full guide and plans1.d4 d5 2.c4 dxc4
The Queen's Gambit Accepted answers the c4 offer by taking, and the next question is the only one that matters: will Black try to keep the pawn? The correct answer is no. The position after 2...dxc4 measures +0.32, and the classical line, where Black returns the pawn and breaks with ...c5, drops to +0.22 — the lowest evaluation among the main answers to 1.d4 measured in this catalogue. Holding the pawn is expensive and fast: trying to win a second with ...Qxd4 measures +7.48, and the c4 pawn was never a won pawn, it was a borrowed tempo.
See the full guide and plans1.d4 d5 2.c4 c6
The Slav Defence (1.d4 d5 2.c4 c6) solves in one move the problem the Queen's Gambit Declined leaves open: it props up the d5 pawn with the c-pawn and keeps the c8-h3 diagonal clear, so the light-squared bishop gets out before ...e6 shuts it in. The position after 2...c6 measures +0.28, and the main line — 4...dxc4 5.a4 Bf5 — sits at +0.29 ten moves in: Black returns the pawn, keeps the good bishop outside the chain and has conceded nothing structural. It is the defence Kramnik, Anand and Ding used to hold match games, and it remains the gold standard of solidity against 1.d4.
See the full guide and plans1.d4 Nf6 2.c4 e6 3.g3 d5 4.Bg2
The Catalan Opening joins two things that do not normally live together: the Queen's Gambit pawn centre and the King's Indian fianchetto. The g2 bishop aims at d5 along the whole diagonal, and the question that defines the opening is what Black does with the c4 pawn — capture and give it back, capture and try to keep it, or ignore it. The position after 4.Bg2 measures +0.15, and the Closed Catalan, where Black simply develops, concedes the most: +0.32. Kramnik used it as a main match weapon and Carlsen keeps it in his repertoire for the same reason — these positions are hard to play badly from only one side.
See the full guide and plans1.d4 Nf6 2.c4 g6 3.Nc3 Bg7 4.e4 d6
The King's Indian (1.d4 Nf6 2.c4 g6 3.Nc3 Bg7 4.e4 d6) is the defence where Black hands over the centre on purpose and bets on tearing it down later, nearly always with ...e5 and an attack on White's king. It is also the one that concedes most among the major defences to 1.d4: the position measures +0.50 after 4...d6, and the Sämisch Attack reaches +0.81 — more than any line in the other nine openings in this batch.
See the full guide and plans1.d4 Nf6 2.c4 g6 3.Nc3 d5
The Grünfeld Defence lets White build the pawn centre of its dreams — e4 and d4 side by side — and then shoots at it from a distance. The position after 3...d5 measures +0.35, one of the highest among major defences, and the number tells the truth about the bargain: Black accepts being worse for a few moves in exchange for a large, fixed target. Where the bargain pays off is the Exchange Variation: the modern version with 7.Nf3 drops to +0.12 after thirteen moves. It is the line Fischer held Spassky with in 1972 and the one Svidler built a career on.
See the full guide and plans1.d4 Nf6 2.c4 e6 3.Nc3 Bb4
The Nimzo-Indian Defence pins the c3 knight on move three and, with it, takes the e4 advance away from White before it exists. The position after 3...Bb4 measures +0.22, and the interesting data in this entry is in the replies: the Capablanca Variation with 4.Qc2 drops to +0.06, the Sämisch with 4.a3 to +0.03, and the Leningrad with 4.Bg5, measured in its main line, reaches −0.22 — Black better. It is the defence Nimzowitsch built to prove that controlling a square beats occupying it, and the engine agrees: none of the four most played replies gives White back the advantage of moving first.
See the full guide and plans1.d4 f5
The Dutch Defence answers 1.d4 with 1...f5 and fights for e4 with a flank pawn, at the cost of weakening its own king's diagonal. The measurement separates the defence's reputation from the reputation of its antidotes. The position after 1...f5 is +0.53. The three best-known anti-Dutch gambits — the Staunton, the Korchnoi and the Krejcik — measure between −0.09 and +0.04: none of them pays. What costs Black most is quiet fianchetto play, which reaches +0.89 against the Classical Dutch.
See the full guide and plans1.d4 Nf6 2.c4 c5 3.d5 e6 4.Nc3 exd5 5.cxd5 d6
The Modern Benoni Defence trades a central pawn for an unbalanced structure: Black gets a queenside majority and one pawn fewer in the centre, and bets that ...b5 arrives before White's centre rolls. The position after 5...d6 measures +0.73 — high, and honest about the risk. Tal and Fischer played it because the position is hard to handle for both sides, not because it is objectively good. The finding in this entry is that White's most aggressive version is not the highest-measuring one: the Taimanov Attack with 8.Bb5+ reaches +0.96, while the modern setup with f4 and Be2 drops to −0.05.
See the full guide and plans1.c4
The English Opening starts on the flank, controls d5 before occupying the centre, and transposes into practically any closed opening depending on Black's reply. The position after 1.c4 measures +0.15 — less than 1.e4 or 1.d4 deliver, and the number is an exact portrait of what the opening offers: not an advantage, but a choice. Botvinnik, Kasparov and Carlsen each used it as a main weapon at different points in their careers, always for the same reason. The opponent has to commit to a structure first, and the English answers afterwards.
See the full guide and plans1.Nf3 d5 2.c4
The Réti Opening attacks Black's centre without occupying it: 1.Nf3 d5 2.c4 aims at the d5 pawn from the flank and leaves Black to decide what to do with it. The number surprises anyone expecting an edge out of the gate: the position after 2.c4 measures −0.06. That is not a flaw in the opening — it is the price of hypermodernism, which trades immediate space for flexibility. Richard Réti beat Capablanca with it in New York in 1924, the Cuban's first loss in eight years, and what won the game was exactly that flexibility: White's setup transposes into the English, the Catalan or the Slav depending on how Black commits.
See the full guide and plans1.f4
Bird's Opening starts with 1.f4, controls e5 from the flank and leads to positions resembling a Dutch Defence with an extra tempo. The measurement shows the cost of that tempo: the position after 1.f4 is −0.18, and White gives up the first-move edge. The most important practical figure is From's Gambit, 1...e5, the most feared reply, which measures +0.37 for White after 4.Nf3 — as long as White does not play 4.Nc3, which loses to mate in three.
See the full guide and plans1.e4 g6 2.d4 Bg7 3.Nc3 d6
The Modern Defence puts the bishop on g7 before anything else and delays the decision about the g8 knight, the c-pawn and the e-pawn. It is the most flexible defence against 1.e4, and the flexibility has a measured price: after 3...d6 the position is +0.69, practically the same as the Pirc. What the entry shows is where that number moves. The immediate 4.f4 Nf6 5.e5, which looks crushing, measures 0.00 after 5...Nfd7 6.Nf3 c5; the Pterodactyl, with ...c5 and ...Qa5, reaches +1.26; and the Monkey's Bum, White's famous gambit, measures −1.25.
See the full guide and plans1.e4 c5 2.Nc3 Nc6 3.g3
The Closed Sicilian declines the exchange on d4 and builds a fixed setup: Nc3, g3, Bg2, d3 and, when the plan calls for it, f4 and Nf3. The position after 3.g3 measures +0.01 — no advantage, and the number is the point. The opening exists to eliminate the twenty thousand lines of the Open Sicilian at a stroke, and the price is playing a level position in which nobody has memorised theory. Spassky took it to world championship matches. This entry measures Black's replies and shows where the setup actually pays: against ...e6 and ...Nd4, where Black commits early, the evaluation rises to +0.47.
See the full guide and plans1.e4 c5 2.c3
The Alapin Variation (1.e4 c5 2.c3) is the most played Anti-Sicilian and the most honest about what it offers: instead of contesting open Sicilian theory, White prepares d4 with pawn support and accepts a smaller edge. Much smaller — the position measures +0.11, against +0.30 for the Sicilian in the starting position. What it delivers, and the evaluation cannot show this, is a whole repertoire that fits into one afternoon of study.
See the full guide and plans1.e4 e5 2.Nc3
The Vienna Game swaps the king's knight for the queen's knight on move two: 2.Nc3 guards e4, prepares f4 and keeps open the choice between a gambit and a quiet fianchetto. The measurement shows a balanced opening. The position after 2.Nc3 is +0.12, half the +0.23 of 2.Nf3, and the Vienna Gambit, the reason for playing it, measures −0.21 after 3...d5. The two gambits after ...Nc6, the Hamppe-Allgaier and the Pierce, measure −1.53 and −1.40. The Vienna buys little-studied positions and pays for them in advantage.
See the full guide and plans1.e4 e5 2.Nf3 Nc6 3.Nc3 Nf6
The Four Knights Game develops all four minor knights before taking any decision, which is why it spent a century with a reputation as a drawing opening. The position after 3...Nf6 measures +0.14, and the main line, the Spanish Four Knights, measures +0.19 — small, but real. What this entry adds is a measurement of the aggressive versions that circulate as shortcuts: the Halloween Gambit, which sacrifices a knight on move four, measures −1.06, and the Belgrade Gambit measures −0.49. Both are entertaining and both are losing, which is more useful information than either one's reputation.
See the full guide and plans1.e4 e5 2.Nf3 d6
The Philidor Defence protects e5 with the d-pawn instead of the knight: 2...d6 is solid, shuts in the f8 bishop and accepts passive play for a structure that is hard to break. The measured price is high for a defence to 1.e4 e5: the position after 2...d6 is +0.72, four times the +0.18 of 2...Nc6. The line that holds the defence together, the Hanham, measures +0.51 and is the lowest White evaluation; the attempts at active play cost more, and the Philidor Countergambit, with 3...f5, measures +1.56.
See the full guide and plans1.d4 d5 2.c4 c6 3.Nf3 Nf6 4.Nc3 e6
The Semi-Slav Defence builds the c6-d5-e6 pawn triangle and deliberately shuts in the c8 bishop — the very bishop the Slav exists to free. The trade-off is well known and the number confirms it: the position after 4...e6 measures +0.28, and the Meran, the line where Black collects on the deal with ...dxc4 and ...b5, drops to +0.18. It is the defence behind the longest and most theoretical games in modern chess, and also the one that produced the Botvinnik Variation, where White gives up a piece on move nine and the evaluation climbs to +0.77 — the sharpest line still played at the top.
See the full guide and plans1.d4 d5 2.c4 e6 3.Nc3 c5
The Tarrasch Defence accepts an isolated pawn on move three in exchange for active pieces and a position that plays itself. The evaluation after 3...c5 is +0.29, and the main line with 9.Bg5 rises to +0.42 — the isolani charges. The version the engine prefers for Black is the Rubinstein, where the exchange on c5 comes before the pin and the position drops to +0.13. Siegbert Tarrasch defended it all his life against the opinion of his age, and Kasparov used it in a world championship. What this entry measures is where the isolated pawn stops being dynamic and becomes merely weak.
See the full guide and plans1.d4 Nf6 2.c4 e6 3.Nf3 b6
The Queen's Indian Defence arises from the same move order that produces the Bogo-Indian: when White plays 3.Nf3 instead of 3.Nc3, the Nimzo-Indian disappears, and ...b6 is the reply that contests e4 with a piece instead of with a pin. The position after 3...b6 measures +0.35, and the finding in this entry is that White's two most ambitious lines — the Petrosian with 4.a3 and the setup with 4.Nc3 and Bg5 — measure +0.01 and 0.00. It is the defence Karpov held dozens of match games with, and the measurement explains why: there is no white plan that presses it without a cost.
See the full guide and plans1.d4 Nf6 2.c4 e6 3.Nf3 Bb4+
The Bogo-Indian Defence is born of a move order: when White plays 3.Nf3 instead of 3.Nc3, the Nimzo-Indian ceases to exist, and ...Bb4+ is the check that keeps the same idea — pin, provoke and trade at the moment the trade costs something. The position after 3...Bb4+ measures +0.30, slightly more than the Nimzo-Indian, and the reason is honest: the bishop on b4 pins nothing, because there is no knight on c3. What it does is force White to spend Bd2 or Nbd2, and the defence lives in that tempo. Efim Bogoljubov took it to two world championship matches, and it stays in the repertoire of anyone wanting a solid defence with half the Nimzo-Indian's theory.
See the full guide and plans1.d4 Nf6 2.c4 c5 3.d5 b5
The Benko Gambit gives up a queenside pawn on move three and asks for nothing in the short term: no attack, no immediate initiative. It asks for two open files, a and b, and a bishop on g7 aimed down the long diagonal — compensation that only pays out in the endgame. The position after 3...b5 measures +0.70, and the main accepted line, fourteen moves later, still measures +0.72. The engine does not see the compensation; decades of practical results do. This entry publishes both sides of the argument, and the finding is that declining with 4.Qc2, which looks prudent, measures −0.41.
See the full guide and plans1.d4 Nf6 2.c4 e5
The Budapest Gambit offers a central pawn on move two to win it back with activity. The position after 2...e5 measures +0.81, one of the highest in this catalogue, and the number needs reading carefully: it measures the position before Black recovers the material. Once recovered, the main lines drop to +0.29 and +0.40 — an ordinary white edge, not a refutation. What this entry measures clearly is the difference between the gambit's two versions: the main one, with 3...Ng4, is playable; the Fajarowicz, with 3...Ne4, measures +3.16 and does not survive accurate play.
See the full guide and plans1.d4 Nf6 2.Bg5
The Trompowsky Attack leaves theory on move two: instead of c4, White plays 2.Bg5 and offers to trade the bishop for the f6 knight before any structure exists. The position measures −0.02 — that is, the move yields no advantage at all. What it yields is something else, and it is why Julian Hodgson and Magnus Carlsen have used it against prepared opponents: no memorised Nimzo-Indian, Grünfeld or King's Indian line survives 2.Bg5, and the game starts counting on move three. This entry measures Black's six most played replies, and the conclusion is that nearly all of them equalise — provided the trade on f6 is accepted without drama.
See the full guide and plans1.d4 d5 2.Nf3 Nf6 3.e3 e6 4.Bd3
The Colle System sets up the same position every time — d4, Nf3, e3, Bd3, Nbd2, c3 — and keeps a single plan in reserve: break with e4 in the centre once the setup is complete. The position after 4.Bd3 measures +0.13, and the most played version, the Colle-Koltanowski with 5.c3, drops to −0.02 in the main line with the break carried out. The number is not a condemnation: the Colle was not built to give an advantage, it was built to be played without study. What this entry adds is exactly where it stops working — and the answer is simple and measurable: when Black's c8 bishop comes out before ...e6.
See the full guide and plans1.Nf3 d5 2.g3 Nf6 3.Bg2 e6 4.O-O Be7 5.d3
The King's Indian Attack is the King's Indian Defence played with White and an extra tempo: Nf3, g3, Bg2, O-O, d3 and, at the right moment, e4. The position after 5.d3 measures +0.02 — the extra tempo does not turn into an advantage, and that says something about the nature of the setup. It does not press; it waits. Bobby Fischer used it against the Sicilian and the French in elite events precisely because the plan is always the same and the opponent's preparation is worth nothing. Where it really works is against structures that have already committed: against the Caro-Kann with ...g6, the position measures +0.86.
See the full guide and plans1.b3
The Nimzo-Larsen Attack starts with 1.b3 and fianchettoes the queen's bishop before deciding the centre: the long diagonal presses e5 and g7, and the rest of the set-up adapts to Black's choice. The measurement gives the opening near equality, −0.04 after 1.b3. The danger lies not in the starting number but in the temptation to attack early: Larsen–Spassky, Belgrade 1970, is the most famous example, and the 10.f4 push that decided it measures −4.13.
See the full guide and plans1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 a6
The Najdorf (1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 a6) is the most studied line in the Sicilian and the one least explained by the move it is named after: ...a6 develops nothing and attacks nothing. What it does is deny b5 to White's knight and bishop and prepare ...b5, buying Black the right to postpone every other decision. The position measures +0.32, and White's sixth move decides the kind of game — from +0.09 with 6.Bc4 to +0.48 with the Bg5 Attack.
See the full guide and plans1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 g6
The Sicilian Dragon fianchettoes the bishop on g7 and points the a1-h8 diagonal straight at the heart of White's position. The position after 5...g6 measures +0.56 — the highest among the major Sicilians, and the reason is plain: Black spends a tempo on ...g6 and opens his own castled position before finishing development. What pays for it is the nature of the game. In the Yugoslav Attack, White castles queenside and both sides attack the enemy king at once; there, half a move of delay decides the game, and preparation is worth more than in any other line in the repertoire.
See the full guide and plans1.e4 e5 2.d4 exd4 3.c3
The Danish Gambit gives up a pawn on move three and, if Black accepts, gives up a second: 3.c3 dxc3 4.Bc4 cxb2 5.Bxb2 leaves White with two bishops aimed at f7 and g7 in exchange for two pawns. Measured, the deal does not close. The position after 3.c3 measures −0.26 and the double acceptance −0.10 — Black stays better in every version. The gambit remains a practical weapon at fast time controls, because the correct defence requires giving material back at the right moment, and giving material back is the least practised skill there is.
See the full guide and plans1.d4 d5 2.c4 Nc6
The Chigorin Defence meets the Queen's Gambit with 2...Nc6, blocking its own c-pawn and betting on active pieces against the classical structure. It is the most unorthodox defence to 1.d4 d5, and the measurement places it halfway: after 2...Nc6 the position is +0.52. The line that costs Black most is the main line, with the bishop exchange on f3 and White's doubled pawn, which reaches +0.87. The one that costs least is 3.cxd5 Qxd5 4.Nf3 e5, which measures +0.07 — near equality in an opening reputed to be risky.
See the full guide and plans1.d4 e5
The Englund Gambit answers 1.d4 with 1...e5, giving up a pawn on move one for a famous trap and little else. The position after 1...e5 is +1.53, a pawn and a half down before move two. The trap is real — if White plays 6.Bc3? in the ...Qb4+ and ...Qxb2 line, Black mates and the position measures −7.17 — but against 6.Nc3 the same line measures +2.29. The cheapest version is the Hartlaub-Charlick, with 2...d6, which measures +0.92.
See the full guide and plans1.d4 d5 2.e4
The Blackmar-Diemer Gambit gives up the e4 pawn on move two and, with f3, offers the f-pawn as well, in return for the open f-file and a quick attack on Black's castled king. The measurement is harsh on the gambit: the position after 2.e4 is −0.65, and after 4.f3, −0.74. Of the four measured defences that accept the second pawn, only one leaves White better, the Teichmann (+0.11), precisely the one that gives up the bishop pair. The Ziegler, with ...c6 and ...Bf5, measures −0.83, and the queen recapture, the Ryder Variation, −1.66.
See the full guide and plans1.e4 b6
Owen's Defence answers 1.e4 with 1...b6 and fianchettoes the queen's bishop against the e4 pawn before contesting the centre with pawns. It is one of the costliest defences to 1.e4: the position after 1...b6 is +0.91, and the main line, with ...e6 and ...c5 against Bd3, measures the same. What the entry shows is where that number drops. The two lines in which Black pins the c3 knight with ...Bb4 measure +0.29 and +0.31, a third of the rest. And the two measured mistakes are Black's and expensive: 3...f5? measures +4.40, and 2...Nf6? reaches +3.17.
See the full guide and plans1.e4 Nc6
The Nimzowitsch Defence answers 1.e4 with 1...Nc6, developing a piece before any pawn and leaving the choice of structure for later. It is a rare defence and sounder than it looks: the position after 1...Nc6 is +0.49. The most useful figure in the entry is that the exchange 3.exd5 Qxd5, with Black's queen centralised early, measures −0.08 after 4.Nf3 — and that the costliest mistake is Black's, not White's: against 4.Nc3, retreating the queen with 4...Qa5 measures +1.90, while 4...Qxd4 wins a pawn.
See the full guide and plans1.b4
The Sokolsky Opening, also known as the Polish or the Orangutan, starts with 1.b4: the pawn gains queenside space and opens the long diagonal for the b2 bishop, at the price of being unprotected from move one. The measurement places the opening a little below equality, at −0.13 after 1.b4. The most played reply, 1...e5, which wins the pawn with ...Bxb4, measures −0.31 after development. The costliest mistake, however, is Black's: in the same line, 3...Nc6? loses the rook to 4.Bxg7 and measures +7.50.
See the full guide and plans1.d4 Nf6 2.c4 d6
The Old Indian Defence is the King's Indian without the fianchetto: 2...d6 prepares ...e5 with the f8 bishop on e7, and the defence trades activity for a compact structure that is easy to set up. The position after 2...d6 is +0.62, and the main line, with ...Nbd7, ...e5, ...c6 and ...Be7, rises to +0.86. The entry's most useful figure concerns the exchanges. The queen trade with 4.dxe5, which takes away Black's castling and looks like the most awkward line, measures −0.01. And the Janowski Variation, with ...Bf5, ranges from −0.13 to +1.63 depending on Black's fourth move.
See the full guide and plans1.e4 c5 2.d4 cxd4 3.c3
The Smith-Morra Gambit gives up a pawn against the Sicilian on move three: 2.d4 cxd4 3.c3 offers the c-pawn for fast development and the open c- and d-files. The measurement states the price plainly: after 3.c3 the position is −0.20, and in the classical formation, with Bc4, Qe2 and Rd1, −0.11. The gambit refutes nothing, but it does not lose either — White plays a fifth of a pawn below equality, in a position Black has to know. And the line's most famous trap works against White: in the Siberian, 9.h3 loses to mate and measures −5.20.
See the full guide and plans1.e4 c5 2.Nf3 e6 3.d4 cxd4 4.Nxd4 a6
The Kan is the most flexible of the open Sicilians: after 4.Nxd4 a6, Black develops no piece and keeps the choice between the bishop on c5, e7 or d6, the knight on f6, c6 or e7, and the queen on c7. The position after 4...a6 measures +0.50, and the flexibility has a price — half a pawn, in the range of the open Sicilians. The entry's useful figure is that the Maróczy, with 5.c4, reputed to be the most awkward test, measures +0.23, and that White's two attempts to win material in the opening measure against White: 6.e5 loses at −1.30, and the capture on g7, −0.32.
See the full guide and plans1.e4 c5 2.Nf3 e6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 Nc6
The Sicilian Four Knights develops both Black knights before any pawn: after 4...Nf6 5.Nc3 Nc6, Black prepares ...Bb4, pinning the knight that defends e4, and ...d5, the break that equalises Sicilians. The position measures +0.48, within the normal range of White's edge in an open Sicilian. What the entry shows is which White moves keep that number. The exchange 6.Nxc6 followed by 7.e5 keeps it (+0.49); the main line with 6.Ndb5 drops to +0.37; and the check 7.Nd6+, which looks like winning the c8 bishop, gives the whole edge away and measures −0.08.
See the full guide and plans1.e4 e5 2.Nf3 Nc6 3.Bb5 Nf6
The Berlin Defence meets the Ruy Lopez with 3...Nf6, attacking e4 instead of defending e5, and became famous as Kramnik's wall against Kasparov in 2000. It is the most solid defence to 1.e4 e5: the position after 3...Nf6 measures +0.20, and the Berlin Wall endgame, without queens and without Black castling, +0.19. The attempts to avoid the endgame do not yield more either — 4.d3 measures +0.22 — and what the measurement exposes are the mistakes. The capture 6...Nxb5?? in the 5.Re1 line measures +9.11, and 5...Nxf2, +3.82.
See the full guide and plans1.e4 e5 2.Nf3 Nc6 3.d4 exd4 4.Bc4
The Scotch Gambit is the Scotch in which White does not recapture the d4 pawn: 4.Bc4 develops the bishop against f7 and leaves Black's pawn on d4 to be regained later — or never. The position measures +0.12, close to equality. What decides is Black's answer on move five. Against 4...Bc5 5.c3, taking with 5...dxc3? measures +0.86; against 4...Nf6, the Max Lange Attack measures +0.34 with 9.fxg7 and −0.25 with 9.Ng5, the most played move. The Möller Attack, which made the gambit famous, ends at −0.09.
See the full guide and plans1.d4 d5 2.Nc3 Nf6 3.Bf4
The Jobava London System is the London with a knight on c3 instead of a pawn: 1.d4 d5 2.Nc3 Nf6 3.Bf4 keeps the bishop outside the pawn chain and adds two ideas the London lacks, the Nb5 jump against c7 and the e4 push. The measurement puts it exactly at equality: +0.01 after 3.Bf4. The most aggressive plan against ...Bf5, with f3, g4 and h4, measures −0.20, and Black's most natural set-up, ...e6 and ...Bb4 pinning the knight, reaches −0.21. The Jobava trades advantage for positions the opponent has not prepared.
See the full guide and plans1.d4 Nf6 2.Nf3 e6 3.Bg5
The Torre Attack brings the c1 bishop to g5 on move three, pinning the f6 knight, and completes development with e3, Nbd2 and c3 against almost any defence. The measurement places the set-up near equality: after 1.d4 Nf6 2.Nf3 e6 3.Bg5 the position measures +0.08, against +0.13 for the London System in the same order. The gap widens against an early ...d5: after 1...d5 2.Nf3 Nf6, the Torre measures +0.02 and the London +0.19, because a knight on e4 hits the g5 bishop with tempo. And the poisoned b2 pawn is no trap: taking it measures +0.17, and what loses is the greed that follows, which reaches +2.42.
See the full guide and plans1.d4 d5 2.c4 c6 3.Nf3 Nf6 4.Nc3 a6
The Chebanenko Slav plays 4...a6 instead of 4...e6 or 4...dxc4: the pawn prepares ...b5 against c4 and leaves the c8 bishop's destination open. The measurement shows the waiting move costs nothing: the position after 4...a6 measures +0.26, practically the same as the Semi-Slav with 4...e6 (+0.28) and the accepted Slav with 4...dxc4 (+0.29). No fifth White move passes a third of a pawn — the highest is 5.a4, at +0.31 — and the system's costliest mistake is White's: after 5.e3 b5, the natural developing 6.Bd3 measures −0.50.
See the full guide and plans1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.b4
The Evans Gambit offers the b-pawn in the Italian: 4.b4 lures the c5 bishop and prepares c3 and d4 with tempo, building the centre the Giuoco Piano usually takes a long time to achieve. The measurement shows a gambit that neither wins nor loses: after 4.b4 the position measures −0.07, and the accepted main line, with 5...Ba5 and 7.O-O, −0.16. The Lasker Defence, which returns the pawn and trades queens, measures −0.20. What the entry records are Black's mistakes: 7...Nge7 in the main line reaches +6.79, and accepting the second pawn with 7...dxc3 ends at +4.79.
See the full guide and plans1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6
The Two Knights Defence meets the Italian with 3...Nf6, attacking e4 instead of developing the bishop, and accepts that White attacks f7 with 4.Ng5. It is the most tactical defence to 3.Bc4, and the measurement shows the tactics favour whoever knows the order. The position after 3...Nf6 measures +0.13. Against 4.Ng5, the classical 4...d5 5.exd5 Na5 measures +0.13 and reaches −0.04 after 10.Ne5; the recapture 5...Nxd5, which opens the way to the Fried Liver, measures +1.51. And the Traxler Variation, with 4...Bc5, measures +1.09 — the famous 5.Nxf7 only equalises, while 5.Bxf7+ measures +0.96.
See the full guide and plans1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.O-O Be7 6.Re1 b5 7.Bb3 O-O 8.c3 d5
The Marshall Attack is Black's gambit in the Closed Ruy Lopez: 8...d5 gives up the e5 pawn for quick development and an attack on White's king before White's queenside pieces leave home. The position after 8...d5 measures +0.41, and the acceptance with 9.exd5 +0.39 — White is a pawn up and better. What the measurement shows is how much that edge shrinks: in the main line, up to 17.Nd2, the position drops to +0.12. The Anti-Marshall lines with 8.a4 and 8.h3, which White plays to avoid the gambit, measure +0.16 and +0.24 — less than accepting.
See the full guide and plans1.e4 e6 2.d4 d5 3.Nc3 Bb4
The Winawer Variation pins the c3 knight on move three and accepts trading the dark-squared bishop for a structure in which White's c-pawn is doubled. It is the most unbalanced line of the French, and the measurement gives White a clear edge: +0.55 after 3...Bb4, +0.62 after 4.e5 c5 5.a3 Bxc3+ and +0.58 in the main position, with 6.bxc3 Ne7. The Poisoned Pawn, the most famous line, keeps the number at +0.69. What the entry records are White's options that do not pay: the gambits with 4.a3 and 4.Bd2 measure 0.00 and −0.14, and 5.Bd2 against ...c5 sits at −0.15.
See the full guide and plans1.e4 e6 2.d4 d5 3.e5
The Advance Variation closes the French centre on move three: 3.e5 gains space, takes f6 from Black's knight and lets Black attack White's chain at its base, with ...c5 and ...Qb6 against d4. The position after 3.e5 measures +0.36, after 3...c5 +0.38, and after 4.c3 Nc6 5.Nf3 Qb6 +0.30 — a normal White edge. The entry records where it disappears. The Milner-Barry Gambit, with 6.Bd3 and the d4 pawn given up, measures −0.84 after 10.Nc3; White's queen on g4 on move four, −1.24. And the line's best-known trap is Black's: taking on d4 too early with 7...Nxd4 loses the queen to 9.Bb5+.
See the full guide and plans1.e4 e6 2.d4 d5 3.Nd2
The Tarrasch Variation defends e4 with the knight on d2 instead of c3: 3.Nd2 avoids the Winawer pin and keeps the c-pawn free for c3, at the cost of shutting in the c1 bishop for a few moves. It is the most economical line against the French, and the measurement places it below the others: +0.19 after 3.Nd2, against +0.62 for the Winawer and the Classical. The entry's useful figure is the gap between Black's replies. 3...c5 measures +0.18 and matches the starting position; 3...Nf6 measures +0.59, and the Guimard, with 3...Nc6, +0.73 — both cost almost half a pawn more.
See the full guide and plans1.e4 c6 2.d4 d5 3.e5
The Advance Variation is the most popular answer to the Caro-Kann: 3.e5 closes the centre and bets that the c8 bishop, which Black takes to f5 before ...e6, will become a target. The position after 3.e5 measures +0.34, and after 3...Bf5 +0.23. What the measurement shows is that the most famous plans against the bishop do not pay: the Short System, with Nf3, Be2 and Be3, measures −0.01, and the pawn attack with 5.g4 and 7.h4 −0.14. The line that keeps the edge is the simplest: 4.h4 h5 measures +0.24, and after 5.c4 e6 6.Nc3 Ne7, +0.33.
See the full guide and plans1.e4 c5 2.Nf3 Nc6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 e5
The Sveshnikov Sicilian answers the open centre with 5...e5, driving the d4 knight away and accepting a permanently weak d5 square in exchange for time and activity. It is the lowest-measuring open Sicilian for White: +0.25 after 5...e5, below the Najdorf and the Classical in the Sicilian entry. What the measurement shows is how much the main line costs White. With 9.Bxf6 gxf6 and Black's doubled pawns, the position reaches 0.00 after 13...Ne7; the alternatives that avoid the exchange, 7.Nd5 and 9.Nd5, keep +0.39 and +0.34.
See the full guide and plans1.e4 c5 2.Nf3 e6 3.d4 cxd4 4.Nxd4 Nc6
The Taimanov Sicilian develops the queen's knight to c6 before deciding the rest: after 4...Nc6, Black keeps the options of ...a6, ...Qc7 and the bishop on b4 or e7, and contests the centre earlier than in the Kan. The position measures +0.49. What the entry shows is the gap between White's tests. The English Attack, with Be3, Qd2 and long castling, is the sharpest: against 9...Na5 it measures +1.02, and against 9...Ne5 +0.28. The quiet lines almost equalise — 6.Be2 measures +0.10 and the 5.Nxc6 exchange +0.06.
See the full guide and plans1.e4 c5 2.Nf3 Nc6 3.d4 cxd4 4.Nxd4 g6
The Accelerated Dragon fianchettoes the bishop before playing ...d6: after 4...g6, Black keeps the option of breaking with ...d5 in one move and avoids the Yugoslav Attack in its most dangerous form. The position measures +0.45, and White's most feared reply, the Maróczy with 5.c4, measures +0.42 after 6...d6 and +0.37 with full development. What the entry records are the traps, and the two biggest are Black's: 8...Na5 against the b3 bishop measures +2.04, and 6...Nxe4 in the Maróczy, +5.46.
See the full guide and plans1.e4 c5 2.Nf3 Nc6 3.Bb5
The Rossolimo Variation avoids the open Sicilian with 3.Bb5: the bishop pins the c6 knight before d4, and White chooses when to trade it and double Black's pawns. The position measures +0.30, the same number as the Sicilian entry and the highest evaluation among the anti-Sicilians measured there. What the entry shows is the cost of each Black reply. 3...e6 measures +0.25 and 3...g6 +0.32; 3...d6 and 3...Nf6 measure +0.59, and 3...Nd4, which looks natural, +0.73. The Bxc6 exchange is not a weapon: with either recapture, the position stays at +0.33.
See the full guide and plans1.e4 c5 2.Nc3 Nc6 3.f4
The Grand Prix Attack meets the Sicilian with 2.Nc3 and 3.f4: White gives up opening the centre with d4 and prepares f5 and a direct attack on Black's king, with the bishop on c4 or b5 and the queen heading to e1 and h4. The measurement is unfavourable from move three: −0.16 after 3.f4, the same number as the Sicilian entry, and the 2.f4 move order measures −0.01. What the entry shows is where the attack holds and where it collapses. The bishop on b5 against ...Nd4 keeps near equality (−0.03); the 6.f5 push, the typical plan, costs four tenths; and in the most natural follow-up to the sacrifice, 8.Bb5 takes the position to −2.31.
See the full guide and plans1.d4 d5 2.e3 Nf6 3.Bd3 c5 4.c3 Nc6 5.f4
The Stonewall Attack is the system in which White sets pawns on c3, d4, e3 and f4, with the bishop on d3, and plays for a knight on e5 and an attack on Black's castled king. The typical order is 1.d4 d5 2.e3 Nf6 3.Bd3 c5 4.c3 Nc6 5.f4, and the measurement does not favour the plan: after 5.f4, the position measures −0.72, against −0.28 for 5.Nf3, which leads to the Colle. The reason is one Black move, 5...Bg4, which gets the c8 bishop out before ...e6 locks it behind the pawn chain. Against the passive reply, 5...e6, the system works and the position measures −0.11.
See the full guide and plans1.d4 d5 2.c4 e5
The Albin Countergambit is the most aggressive answer to the Queen's Gambit: 2...e5 gives a pawn to drive another into d4 and hinder White's development. The measurement is harsh on Black. After 2...e5, the position measures +0.79, and after 3.dxe5 d4 4.Nf3 Nc6, +0.74. Against 5.g3, only one move holds: 5...Nge7, at +0.67. The three most natural developing moves — 5...Be6, 5...Bg4 and 5...Bf5 — measure between +1.42 and +1.49. What keeps the Albin alive is the Lasker Trap, 4.e3? Bb4+ 5.Bd2 dxe3, where 6.Bxb4?? ends with a pawn promoting to a knight.
See the full guide and plans1.e4 e5 2.Nf3 f5
The Latvian Gambit is the King's Gambit with colours reversed and a tempo down: 2...f5 hits e4 and leaves e5 undefended on move two. The measurement is clear: after 2...f5, the position measures +1.73. The main answer, 3.Nxe5 Qf6 4.d4 d6 5.Nc4 fxe4, measures +1.73, with equal material and Black behind in development. The most popular club move, 3.Bc4, also gives an edge but demands precision: the line with a queen trade ends at +0.99, and the developing 4.Nc3?? loses the knight. The Latvian lives on traps along the e8-h5 diagonal, and the best known of them catches White: 4.Qh5+? g6 5.Nxg6, which measures −4.79.
See the full guide and plans1.e4 e5 2.Nf3 Nc6 3.c3
The Ponziani Opening trades development for the centre: 3.c3 prepares d4 and gives c3, the knight's square, to a pawn. The measurement does not favour it. After 3.c3, the position measures −0.20, with 3...d5 as the best reply. In the most played defence, 3...Nf6 4.d4, the capture 4...Nxe4 measures −0.02 and ties with 4...exd4 as the best move, while the developing 4...d5 measures +0.41. For White, the answer to the capture is 5.Bd3 (−0.01); the popular 5.d5 measures −0.29, and the recapture 5.dxe5? drops to −0.93.
See the full guide and plans1.e4 e5 2.Bc4
The Bishop's Opening brings the bishop to c4 on move two and postpones the decision about the g1 knight and the f-pawn. It is an opening of transpositions: depending on Black's reply, the game can become a Vienna, an Italian or an open game of its own, and White chooses the moment. After 2.Bc4, the position measures −0.03. Against 2...Nf6, the most played reply, the moves that hold equality are 3.Nc3 (−0.04) and 3.d3 (−0.08); 3.Nf3?! gives up the e4 pawn and measures −0.49, and 3.f4? measures −1.13. The modern main line, with 3.d3 c6 4.Nf3 d5 5.Bb3 a5, stands at +0.04.
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