Insufficient material

In chess, material means the pieces remaining on the board. Material is called insufficient when those pieces cannot produce checkmate, an attack on the king with no legal reply. Bare kings, king and bishop against king, and king and knight against king are familiar examples.

The rules of the International Chess Federation do not decide this through a fixed table of piece values. For the whole position to end immediately as a draw, it must be a dead position: neither player can checkmate through any possible sequence of legal moves. It is not enough that mate cannot be forced against correct defense.

When time expires, the test can be one-sided. If the player whose chess clock still has time could not checkmate the opponent through any legal sequence, the result is a draw even though the other clock reached zero. Insufficient material therefore does not simply mean having few pieces or being behind in material.