Rule of the square: a practical example
Imagine a square whose side runs from the pawn to its promotion rank. If the defending king can enter that square with the relevant side to move, it can usually catch the pawn in the simplified case. A starting pawn's two-square option must be included.
How to use the idea in your games
Treat the rule as a first calculation, not a substitute for one. Checks, blocking pieces, king support, and a possible double advance can change the result.
A useful study question
Can you explain rule of the square in your own words, identify it in a position, and describe when the idea does not apply? Test the explanation on a legal board before relying on it.
Connect the ideas
Passed pawn, Promotion, King activity are useful next concepts. Follow the links to compare definitions and examples, then return to the complete chess glossary whenever an unfamiliar term appears.
Sources & further reading
References checked September 5, 2026. Linked services are independent of ChessRankings.com™.