Chess endgames
The Rule of the Square in Chess Endgames
The rule of the square is a quick way to tell whether a king can catch a passed pawn with no help from other pieces. Draw a square from the pawn to its promotion rank. If the king can step into that square on its move, it catches the pawn.
Examples
1. Ke4 a4 2. Kd3 a3 3. Kc2 a2 4. Kb2 a1=Q+ 5. Kxa1
The pawn on a5 has a square with corners a5, e5, e1, and a1. White to move steps into it with Ke4 and reaches the pawn in time, taking the new queen on a1.
1... a4 2. Ke4 a3 3. Kd3 a2 4. Kc2 a1=Q
With Black to move, the pawn goes to a4 and the square shrinks to a4, d4, d1, and a1. The king on f4 cannot step into it, and the pawn promotes one move ahead of the king.
How to draw the square
Count the squares from the pawn to its promotion square, including both. Then mark the same distance sideways toward the defending king. The square has the pawn and the promotion square as two of its corners.
If it is the defender's move, the king catches the pawn if it can move into the square. If it is the pawn's move, imagine the pawn one square further on and draw the smaller square instead, or simply check whether the king is already inside the larger one.
The exceptions
A pawn on its starting square can advance two squares on its first move. Draw the square as if the pawn already stood one rank further forward, on the third rank for White or the sixth rank for Black.
The rule assumes a clear path. If the king's own pieces or pawns block its route, it may not get there in time even when it stands inside the square. If the attacker's king or pieces cover squares on the defending king's path, the count changes too. The rule also ignores everything else on the board, such as checks or a second passed pawn.
Why it saves time
In a race between a king and a pawn, counting moves one by one is slow and easy to get wrong. The square gives the answer instantly. Use it before you trade into a pawn ending, and use it when deciding whether you can let the opponent's pawn run while your king does something else.
Common questions
Does the rule of the square work when the pawn is defended?
The rule only tells you whether the king can reach the pawn's path in time. If the pawn is defended by its own king or another piece, catching it does not mean winning it.
Does the rule of the square work for rook pawns?
Yes. The square works the same way for a pawn on any file. It is drawn toward the side where the defending king stands.
Keep learning
Find these moments in your own games.
Paste a game into the free analyzer to find the moves that cost you, with each mistake explained in plain English. Three analyses are free, with no email or card.
Analyze a game free →Practice with a coach beside you.
Play a human-like opponent at your level while the coach explains your moves as you go. The first coached game is free.
Play a free coached game →