Key Squares

Key squares are squares a king must reach to win a pawn endgame. If the king reaches a key square, the pawn can promote against any defence.

Key squares for a pawn on e5

White pawn is on e5. Its key squares are d6, e6, and f6, one rank ahead of the pawn.

FEN: 4k3/8/8/4P3/8/8/8/4K3 w - - 0 1

a b c d e f g h
8 . . . . k . . . 8
7 . . . . . . . . 7
6 . . . . . . . . 6
5 . . . . P . . . 5
4 . . . . . . . . 4
3 . . . . . . . . 3
2 . . . . . . . . 2
1 . . . . K . . . 1
  a b c d e f g h

King reaches a key square

White king is on e6 and White pawn is on e5. The king stands on a key square, so the pawn can promote.

FEN: 4k3/8/4K3/4P3/8/8/8/8 w - - 0 1

a b c d e f g h
8 . . . . k . . . 8
7 . . . . . . . . 7
6 . . . . K . . . 6
5 . . . . P . . . 5
4 . . . . . . . . 4
3 . . . . . . . . 3
2 . . . . . . . . 2
1 . . . . . . . . 1
  a b c d e f g h

Key squares for a pawn on d5

White pawn is on d5. Its key squares are c6, d6, and e6. White king on d6 stands on a key square.

FEN: 4k3/8/3K4/3P4/8/8/8/8 w - - 0 1

a b c d e f g h
8 . . . . k . . . 8
7 . . . . . . . . 7
6 . . . K . . . . 6
5 . . . P . . . . 5
4 . . . . . . . . 4
3 . . . . . . . . 3
2 . . . . . . . . 2
1 . . . . . . . . 1
  a b c d e f g h

Key points

Key squares depend on the pawn. A pawn on e5 has key squares d6, e6, and f6.
A pawn on d5 has key squares c6, d6, and e6. The pattern is the three squares one rank ahead of the pawn.
Reach a key square with your king before pushing the pawn too far.
A king on a key square cannot be driven away in time. The pawn will promote.
Key squares tell you where the king must go.

Try it Yourself

Edit the code, then press Run.

Running is simulated · Rust Playground

Exercise

White pawn is on e5. Which square is a key square for this pawn?

e6 e4 d4 f4