Best Chess Move CalculatorChess Evaluation Explained: What +0.30, +1.50 and M3 Mean
Every chess move calculator prints a number next to its best move. That number is the engine's verdict on the position, and once you can read it, the results become far more useful than a bare "play this."
The scale is the same idea everywhere: Stockfish in our free calculator, the Lichess analysis board, and the evaluation bar in ChessHelper (chesshelper.ai) all show who is better and by roughly how much. This guide explains the scale and then walks through five positions we checked with Stockfish 10 at depth 18.
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The unit is the pawn
Engine scores are measured in pawns, usually written with two decimals. +1.00 means the engine rates White's position as worth about one extra pawn. Internally engines count in centipawns, hundredths of a pawn, so +1.00 is 100 centipawns.
The sign tells you who is better. A plus sign favors White and a minus sign favors Black. Some apps show the score from the side to move instead; our calculator and most analysis boards always use White's point of view, so -0.80 always means Black is better.
The number is not a material count. A position with equal material can score +2.00 because one king is about to be mated, and a pawn-up position can score 0.00 because the extra pawn cannot be used. Think of the score as "how much material this position is worth," not "how much material is on the board."
A practical scale for club players
These bands are approximate and engine-dependent, but they are a reasonable way to translate the number into words.
| Score | What it usually means | At club level |
|---|---|---|
| 0.00 to ±0.30 | Equal | The better player usually wins |
| ±0.30 to ±0.70 | Slight edge | Easier to play, nowhere near decisive |
| ±0.70 to ±1.50 | Clear advantage | Worth a pawn or good piece play |
| ±1.50 to ±3.00 | Large advantage | Often winning with careful play |
| beyond ±3.00 | Decisive | Usually a piece up or a crushing attack |
| M3, -M2 | Forced mate | Mate in that many moves with best play |
Mate scores
When the engine finds a forced checkmate, it stops showing pawns and shows the number of moves to mate. Our calculator writes this as +M3 for White mating in three and -M2 for Black mating in two. Other tools write #3 or M3. A mate score outranks any pawn score: +M12 is better than +25.00, because mate ends the game.
The count is in full moves by the winning side, assuming the defender resists as long as possible. If you play a slower winning move, the mate number can go up or turn back into a large pawn score. That is fine; a win is a win.
What "equal" means at your level
An engine's 0.00 says that perfect players would draw. It does not say the position is easy for both sides. Positions with balanced scores can still be full of traps, and in games between club players the side with the easier plan, the safer king or simply more time on the clock often wins an "equal" position.
Small advantages work the same way. +0.40 is a real edge between grandmasters. Between two 1300 players it will usually change hands several times before the game ends. Use the score to understand who stands better, then pay more attention to the moves the engine wants than to the decimals.
Position 1: equal, three good moves
After 1.e4 e5 2.Nf3 Nc6 3.Bc4, the Italian Game, it is Black's move. Stockfish 10 at depth 18 gives:
| Move | Score (White) |
|---|---|
| 3...Nf6 | +0.05 |
| 3...d6 | +0.19 |
| 3...Bc5 | +0.41 |
All three are normal opening moves and all three keep the game within the equal or slight-edge range. A gap of a few tenths in the opening is not a reason to change your repertoire; it is a signal that both sides have a playable game.
Position 2: about +1.50 after a dubious move
After 1.e4 e5 2.Nf3 Nc6 3.Bc4 Nd4, Black has moved the same knight twice and left the e5 pawn without its defender. This is the Blackburne Shilling Gambit, a trap opening.
Stockfish 10 scores 4.O-O at +1.49 and 4.Nxd4 at +1.43. White has gained time and Black's development is behind, so the engine already sees an advantage worth roughly a pawn and a half, with material still level. The tempting 4.Nxe5 is a different story; our improvement guide uses that capture as a blunder-check example.
Position 3: about +2.00, a pawn up with the better game
In Legal's trap, after 1.e4 e5 2.Nf3 d6 3.Bc4 Bg4 4.Nc3 g6 5.Nxe5, Black should not take the queen. With White to move before 5.Nxe5, Stockfish 10 at depth 18 picks that capture, scores it +2.04 and expects 5...dxe5 6.Qxg4. White has won a pawn and keeps the more active pieces, which is why the score sits higher than a plain +1.00. Our guide to how calculators work shows how this score changes with depth.
Position 4: a mate score
After 1.e4 e5 2.Bc4 Nc6 3.Qh5 Nf6, Black has attacked the queen but forgotten about f7. The engine's first line reads +M1: 4.Qxf7# is checkmate.
The second and third lines in the same search show how much the score depends on finding the right move. Retreating with 4.Qd1 scores -1.56 and 4.Qe2 scores -2.25, because Black then wins the e4 pawn with a strong position. The same position is either mate or clearly worse for White, depending on one move.
Position 5: a pawn up and still a draw
In the king and pawn ending below, White has an extra pawn, but Black's king stands directly in front of it.
Stockfish 10 at depth 20 scores the position +0.09, which is the engine's way of saying "draw." Black keeps the opposition and White cannot force the pawn through. Material is a pawn up, the evaluation is level, and the evaluation is correct. Without endgame tablebases an engine can show a small non-zero number in a dead draw; anything this close to zero in a simple ending means the same thing.
Why scores differ between tools
Run the same position on two sites and you will rarely get identical numbers. Engines differ in version, evaluation method and search depth, and some sites show scores from the side to move. Stockfish 10 also uses a classical evaluation that tends to run higher in the opening than current neural-network versions. Compare the ranking of moves and the rough band, not the second decimal.
Some tools also translate the number into a picture. ChessHelper and most analysis boards draw an evaluation bar, which is handy at a glance, while some apps convert scores into a win percentage. Underneath, they all start from the same kind of engine score explained here.
Related guides
Keep going with the rest of our guides.