Chess blunders, mistakes, misses and inaccuracies explained
By the Kibitzz team · · 3 min read
Game analysis labels each move by how much it hurt your position: an inaccuracy is a small slip, a mistake is a clearly worse move, a miss is failing to punish your opponent's error, and a blunder throws away a large part of your advantage or loses material or the game. The labels come from how much a move changes the engine's evaluation.
How do tools decide the labels?
An engine such as Stockfish evaluates the position before and after every move. The tool converts those evaluations into your chances of winning and compares what you played with the best move. The bigger the drop, the more serious the label.
The exact cutoffs differ from site to site, so the same move can get a different label in different programs:
- Chess.com's Game Review measures expected points lost: roughly 0.05 to 0.10 for an inaccuracy, 0.10 to 0.20 for a mistake and 0.20 or more for a blunder.
These thresholds are the sites' own and can change over time, so treat the numbers as a guide to how the labels work, not as a rulebook.
What is an inaccuracy in chess?
An inaccuracy is a move that is playable but not the best. It gives up a small part of your advantage, or lets the opponent equalize slowly, and it rarely decides a game on its own. Most strong games contain several.
What is a mistake in chess?
A mistake is a move that clearly worsens your position, for example allowing a strong plan or losing a pawn, but does not lose the game on the spot. A mistake often hands the opponent the initiative.
What is a miss in chess?
A miss is a label used by Chess.com. It marks a move where you failed to capitalize on your opponent's error: they slipped, a winning or much better continuation was available, and you played something that left the position equal or worse for you.
A miss is different from a mistake because the move itself may not look bad. What went wrong is the chance you did not take. Misses are common in over-the-board games, where you have to notice for yourself that your opponent has just erred. Lichess has no separate miss label, so the same move there shows up as an inaccuracy or mistake, or as nothing at all.
What is a blunder in chess?
A blunder is a serious error that swings the evaluation heavily, such as hanging a piece, missing a mate or walking into a tactic. Blunders are usually the moves that decide a game.
What are the other labels, such as brilliant and best?
Analysis tools also label good moves. Chess.com uses Best, Excellent and Good for strong moves, Great for a move that was critical to the outcome, and Brilliant for a good piece sacrifice that was not already obviously winning. The error labels above are only the downside half of the scale.
Why does context matter?
A move that looks like a blunder in a balanced position may barely matter if you were already completely winning, and the reverse is also true. Labels tell you where to look, not what to conclude. Always ask whether a human could realistically have found the better move, and why you played the one you did.
How do you use the labels to improve?
Count your blunders, mistakes and misses across several games and sort them: tactical oversight, wrong plan, opening gap or time pressure. The biggest group is what to practice first. Many players find that cutting blunders and converting misses raises results faster than learning new openings.
Kibitzz flags blunders, mistakes and brilliant moves from its Stockfish analysis, gives each player an accuracy score, and explains in plain English what changed at the critical moments of the game.