LibreChessChess, explained simply

Chess rules

Pawn Promotion and Underpromotion

Published Updated

LBy
Sources and chess examples are checked before publication. How LibreChess verifies its content.

When a pawn reaches the far side of the board — the 8th rank for White, the 1st for Black — it must promote, immediately becoming a queen, rook, bishop, or knight of its own colour. A queen is the usual choice, but the position can make another piece better.

On this page
  1. Promotion is mandatory — the choice is which piece
  2. Underpromotion: choosing something other than a queen
  3. Why promotion decides endgames
  4. Keep learning

Promotion is mandatory — the choice is which piece

A pawn that reaches the last rank cannot stay a pawn; it becomes a piece as part of the same move. You may pick a queen, rook, bishop, or knight regardless of how many of that piece you already have. That means two or more queens of one colour are legal. Queen promotion is written, for example, as e8=Q.

♚♟♚
White to move. Push the a-pawn to a8 to promote — take a new queen.

Underpromotion: choosing something other than a queen

Promoting to a rook, bishop, or knight is called underpromotion, and it can be the best move. A knight may give a check or fork that a queen cannot. A rook or bishop can sometimes avoid stalemate or preserve a particular line of control. Calculate the resulting position: underpromotion is correct only when the extra powers of a queen would be unhelpful or the different piece creates a concrete gain.

Compare every legal promotion when the obvious queen would stalemate, allow a tactic, or miss a forcing knight move.

Why promotion decides endgames

Promotion is central to many endgames. A passed pawn has no opposing pawn ahead of it on the same or an adjacent file, although a king or piece may still stop it. Endgame play often involves creating, blockading, escorting, or racing such pawns. In king-and-pawn endings, the position of the kings frequently decides whether a pawn can promote.

Do you have to promote to a queen?No. Promotion is mandatory, but you choose the piece — queen, rook, bishop, or knight. A queen is usually best, while an underpromotion may give a unique check, avoid stalemate, or meet another concrete need.
Can you have two queens?Yes. You can promote as many pawns as reach the last rank, so it is entirely legal to have two or more queens on the board.
Why would anyone promote to a knight?Because a queen cannot move like a knight. If only an L-shaped jump delivers a winning check or fork, a knight promotion is stronger than a new queen.

Play free vs Stockfish

Keep learning