What is a king fork in chess?

A king fork is a type of fork in which the king steps to a square where it attacks two undefended enemy pieces at the same time. Because the king moves only one square in any direction, both targets must be immediately adjacent; king forks are therefore rare and occur almost exclusively in endgames.

The white king sits between a black knight and rook, attacking both. Neither piece is able to defend the other!

What makes a king fork different from a regular fork?

Most forks use long-range pieces or knights that can strike from a distance. A king fork is different because the king's range is exactly one square. That means both targets must be very close together, which makes king forks uncommon in the opening and middlegame, when the board is crowded and the king stays sheltered. If they appear, it will almost certainly be in the endgame, once most material has been traded and the king can advance safely.

The white king advances to fork both black knights. Engine-verified position, Elo 596.

How do you defend against a king fork?

Prevention is key. Keep your pieces defended (or able to defend each other) in the endgame so the opposing king can't attack both. Since pawns are especially vulnerable, keep an eye out for king movements toward unprotected pawns. The king is slow, so its intentions are usually telegraphed quite early!

If you are already forked, a simple move with a king or pawn might serve to protect both targets. Additionally, chances are you can move one piece out of reach while defending the other.

Both the white knight and bishop are under attack from the black king, but the knight can simply drop back and defend the bishop.

See it in action

Example 1: King fork in the endgame

Find the fork.

Solution: The white king moves one square diagonally up-left to fork both the rook and the bishop. Black can only save one, so the king captures the bishop.

Example 2: King fork wins a pawn

Find the fork.

Solution: The white king moves one square diagonally down-left to fork two pawns. Black saves one, the white king captures the other.

Example 3: Turn a check into a fork

Find the fork.

Solution: The white king moves one square diagonally up, getting out of check and forking the knight and rook. The black rook moves, so the white king captures the knight.

Frequently asked questions

Can a king fork deliver check?

No. The king can never give check to another king. A king fork only targets non-king pieces. If the two kings were adjacent, the position would be illegal because kings can never stand next to each other.

Are king forks common?

They are rare compared to knight forks or queen forks. King forks appear almost exclusively in endgames with few pieces left on the board. However, recognizing them can decide the outcome of a close endgame.

Can a king fork win a queen?

No. Since a king can't move into check, it cannot legally approach an enemy queen from any direction. Keep your king away from queens!