What is a mistake in chess?
A mistake loses between 100 and 199 centipawns — a full pawn's worth of advantage or more, without quite throwing the game away. That is the threshold at which the assessment of the position genuinely changes.
Threshold
Mistake — 100 to 199 centipawns lost against the engine’s best line.
A pawn is the threshold for a reason
A centipawn is a hundredth of a pawn, so 100 centipawns is a whole pawn's worth of advantage. So a mistake is, by definition, giving away at least a pawn's worth of position — not necessarily a pawn, but that much advantage.
Below it sits the inaccuracy band, from 50 to 99: something was conceded, but a good position stays good. Above 200 is a blunder, where the result itself usually changes.
The most useful grade to study
Blunders are memorable and often obvious in hindsight — a hanging piece, a missed mate. Mistakes are the ones that repeat, because the thinking that produced them felt reasonable at the time.
That is why a pattern of mistakes in the same structure is worth more than any single blunder. A blunder is an accident; the same mistake across fifteen games is a gap in understanding, and it is the thing that can actually be fixed.
Frequently asked questions
What is the difference between a mistake and a blunder?
The size of the loss. A mistake gives up 100 to 199 centipawns; a blunder gives up 200 or more. A mistake usually worsens the position, while a blunder usually decides it.
How many mistakes is normal in a club game?
Two or three per game is ordinary around 1200 to 1600. The number matters less than whether they cluster — repeated mistakes in one opening or structure point at something learnable.