♞Reflex Chess

When neither side has enough to mate

Some positions are drawn the moment they appear, because no sequence of legal moves could ever produce a checkmate. The rules end the game there rather than let two players shuffle kings for an hour.

Insufficient material is a draw that happens by itself. Nobody claims it and nobody agrees to it: the moment the last piece that could have mated leaves the board, the game is over and level.

The table, answered by the engine

Each of these positions was handed to the same rules engine that runs the trainer, and the verdict beside it is the engine's answer to "could a checkmate ever happen here".

A drawn position with a piece on it

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King and bishop against a bare king. The bishop has seven moves and none of them can ever lead anywhere, because a bishop and a king cannot construct a mate between them. The game is over the moment this position appears.

The two entries that surprise people

Two knights is not an automatic draw

King and two knights against a bare king cannot force mate. A defender who plays sensibly cannot be mated. But a mate position does exist, and a defender who cooperated could walk into it, so the rules do not end the game. Play it out, get bored, and claim under the fifty-move rule instead.

If the defender has a pawn, two knights can sometimes force a win, which is the strange and beautiful corner of endgame theory known as the Troitsky line. That is a long way from any game you will play.

Same-coloured bishops are drawn, opposite-coloured ones are not

Two bishops on the same colour of square can never both attack the same square, and cannot construct a mate. Bishops on opposite colours can, with help, so the game continues, and in practice it is a dead draw that ends by the fifty-move rule.

In a real endgame the phrase "opposite-coloured bishops" usually means something else entirely: a middlegame or endgame where each side has one bishop and they run on different colours, which makes attacks strong and endgames very drawish. Being two pawns up with opposite bishops is often not enough to win.

On the clock

The rule has a second job. If a player runs out of time, they normally lose, but if the opponent has insufficient material to mate then the game is a draw instead. So a lone king can never win on time. Organisations differ on the edge cases, particularly a lone knight or bishop where a helpmate is technically possible, so check your event's rules if it matters.

What you actually need to mate

Questions people ask

What counts as insufficient material in chess?

King against king, king and bishop against king, king and knight against king, and king and bishop against king and bishop when both bishops are on the same colour of square. In each of those the game is drawn immediately and automatically.

Is king and two knights a draw?

It cannot be forced against correct defence, but it is not declared a draw by the insufficient material rule, because a mate position exists and a cooperating defender could reach it. In practice the game ends by the fifty-move rule.

Can you win on time if you only have a king?

No. If your opponent's flag falls and you have no material that could possibly deliver checkmate, the result is a draw rather than a win.

Is king and pawn against king a draw?

Not by insufficient material, because the pawn can promote. Whether it is actually a draw depends entirely on the position, which is what the opposition and the rule of the square are for.

Related

Insufficient material sits under How a game ends in the reference. Nearby: