How accurate was your game? Chess accuracy checker
Paste a game from Chess.com, Lichess or anywhere. Stockfish grades every move for both sides, and Coach Bjorn explains your mistakes.
Which side were you?
Légal Trap, White won
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How accuracy works
Accuracy grades your moves, not the result. Stockfish compares each move with its own choice and grades it: best, good, inaccuracy, mistake or blunder. Each grade has a score, and your accuracy is the average. A game you won can score lower than one you lost, if you won it with blunders your opponent didn't punish.
Questions
How is chess accuracy calculated?
Stockfish grades every move, and each grade has a score: 100 for the engine's own move, 92 for a good move or a book move, 55 for an inaccuracy, 30 for a mistake or a missed chance, and 10 for a blunder. Your accuracy is the average over your moves. A move with only one legal option doesn't count.
Why is my accuracy different from Chess.com or Lichess?
Every site uses its own formula and engine settings, so the same game can score differently. Compare games checked on the same site. Here, the number matches what KingChess's Game Review shows.
What counts as a blunder or a mistake?
A blunder gives away 2 pawns or more of value against Stockfish's best move, a mistake 1 to 2, an inaccuracy half a pawn to 1. A missed chance is when your opponent handed you a big advantage and your move gave it back.
Why does Coach Bjorn only explain the first half?
The accuracy and every graded move are free for the whole game. Bjorn's explanations cover your moves in the first half of a pasted game. With a free account he reviews your own Chess.com and Lichess games.
How long does a check take?
Usually under a minute: Stockfish looks at every position in the game. Games longer than 100 moves aren't checked.
How many games can I check?
10 a day. To keep going, type your username below and Bjorn reviews your latest game free.
What happens to my game?
The moves are sent to KingChess's engine and kept in memory for a while, so checking the same game again is instant. Nothing is saved to an account.
Coach Bjorn
Want this for your own games without pasting? I'll review your latest one free. Type your username and pick your site.