Inaccuracy
An inaccuracy is the mildest error label in game review, given to a move that is playable but gives up a small amount of advantage compared with the engine's better alternative.
Also called: inaccuracy mark
In game review, moves that cost a little evaluation are usually marked as inaccuracies, the lightest of the three error grades, with mistakes and blunders above it. The exact cutoff differs between tools, so there is no single agreed size. An inaccuracy rarely changes the result by itself. It might be a slightly passive retreat, a pawn move that loosens your structure, or a natural developing move when a sharper one was available. Club players meet many of these in every game, and that is normal; even strong players collect them. The common mistake is treating each one as a failure to fix. Chasing every small mark wastes study time and can make you play timidly. A better habit is to look for patterns among your inaccuracies across several games. If many of them come in the same phase, such as the early middlegame, or the same kind of decision, such as when to exchange pieces, that is a genuine area to train. Otherwise, save your attention for the larger swings that decide games.
Computer terms such as "Inaccuracy" are most useful next to a coach who reads your games with you, which is how a first lesson with George Li works.
Related terms
A mistake is a game review label for a move that clearly worsens a position, costing a meaningful share of the advantage, though it is less severe than a blunder that throws the game away.
A blunder is a very serious error, such as leaving a piece undefended or missing a decisive tactic, that swings the evaluation so far that a good position turns bad or a bad one becomes lost.
The best move is the move an engine rates highest in a given position after searching, usually shown first in its list of candidate lines and marked with the strongest evaluation.
A game review is an automatic engine pass over a finished game that marks each move, shows how the evaluation changed and points out the turning points, mistakes and missed chances.
Accuracy is a percentage produced by analysis software that summarizes how closely a player's moves matched the engine's preferred choices over a game, with higher numbers meaning fewer costly errors.
Guides that go further
What to decide first, the questions to ask, what a first lesson should show and the red flags to avoid.
How much does chess coaching cost?
Published rates for private, group and subscription chess coaching, with the source and the date of each.
A game review, a read on your level and a written study plan from George Li.
Want to spot this in your own games?
A first lesson starts with your games: George reviews them and builds a study plan around what he finds.