Chess move classifications, explained.
Brilliant, Great, Best, Excellent, Good, Book, Inaccuracy, Mistake, Miss, Blunder and Forced: what each label means, and the exact rule this site's game review uses to give it.
- BrilliantThe engine's best move, and it really gives material away: checked with exchange maths on the board, not guessed from the score, and clearly better than not sacrificing.
- GreatThe only good move: every alternative throws away at least 10% of your winning chances.
- BestThe engine's top choice in the position.
- ExcellentNot the top move, but it costs under 2% of your winning chances.
- GoodCosts between 2% and 5% of your winning chances.
- BookOpening theory: a move strong players really choose here, from 1.8 million of their games.
- InaccuracyGives away 5–10% of your winning chances.
- MistakeGives away 10–20% of your winning chances.
- MissYour opponent just made a mistake and you let it go unpunished.
- BlunderGives away 20% or more, or walks into a forced mate.
- ForcedThe only legal move.
The rules in detail
The same rules for every game, from your blitz games to world championships.
Winning chances, not pawns
Stockfish evaluates the position before and after your move, and both evaluations are turned into winning chances (your expected score) with Lichess's win-probability curve. A move's label depends on how much of those chances it gives away compared with the engine's best move, in the bands Chess.com publishes. That's why dropping a pawn's worth matters far more in a level position than when you're a rook up.
Brilliant
A good sacrifice. All of these must hold:
- it's the engine's best move;
- it really gives material away: a piece left where it can be taken, or put there, checked with exchange arithmetic on the board rather than guessed from the score;
- it beats the best move that gives nothing away;
- you aren't worse after it;
- you weren't already completely winning without it;
- it isn't a way out of check or a promotion to a queen.
“Completely winning” depends on the players' rating. Below about 2600, players turn an advantage into a win less surely than engines do, so the same evaluation counts as less decided.
Great
The only good move: the engine's best, when every other move gives away at least 10% of your winning chances. Like Brilliant, it isn't given when the game is already decided, when you're worse after it, or for simply taking a piece that was free.
Miss
A chance let go. Your opponent's last move was a mistake or a blunder, and yours gives back at least 10% of your winning chances, but leaves you no worse than you were before their mistake. If it leaves you worse, it's a Mistake or a Blunder instead.
Book and Forced
Book moves are opening theory: positions reached in at least 20 of 1.84 million games between strong players, from over-the-board events and the strongest online games, for as long as the game stays in theory. Forced is the only legal move.
Accuracy
Each move's accuracy comes from the winning chances it gives away, with Lichess's formula. The game's accuracy combines them and is put on Chess.com's scale, fitted on games Chess.com reviewed; it usually lands within 3 to 4 points of Chess.com's number.
Questions
About the labels.
What is a brilliant move in chess?
A good sacrifice: the best move in the position, and it really gives material away. You must not be worse after it, and you must not have been completely winning without it.
What's the difference between Best and Great?
Best is the engine's top move. Great is a Best move that was also the only good one: every alternative gives away at least 10% of your winning chances.
What is a Miss?
Your opponent had just made a mistake or a blunder, and your reply let the chance go: it gives back at least 10% of your winning chances, though you end up no worse than before their mistake.
Is a Blunder always a losing move?
No. A blunder gives away 20% or more of your winning chances, or walks into a forced mate. From a winning position, a blunder can leave you only equal.
Why is my move Excellent and not Best?
Best is only the engine's top choice. A different move that costs under 2% of your winning chances is Excellent: in practice just as good.
See the labels on your own games.
Enter a Chess.com or Lichess username or paste a PGN, then step through the game move by move.