Inaccuracy (chess)

In chess terminology, an "inaccuracy" is a move which causes a loss in position of at least 0.3 points in a computer analysis, relative to the best move possible.

Stronger terms are used for even weaker moves:

• a "mistake" is a move that causes a loss of at least 0.9 points in position, relative to an optimal move.
• a "blunder" is a move which typically causes an unnecessary loss in material, amounting to a loss of at least 2 points compared with the best available move. The top blunders in chess championships, which are sometimes the result of having little time left on the clock, are explained in a video explanation.