What happens when a pawn reaches the end
Every pawn on the board is a queen that has not arrived yet. Get one to the far rank and it stops being a pawn on the spot, which is why endgames with one pawn each are worth taking seriously.
- Queen, rook, bishop or knight
- No limit on queens
- Not optional
A pawn that reaches the eighth rank, or the first rank if you are Black, is immediately replaced by a queen, rook, bishop or knight of your own colour. It happens as part of the same move, you choose which piece, and you may not choose a king and may not choose to stay a pawn.
A pawn becoming a queen
The pawn steps to e8 and comes back as a queen. Notation writes it e8=Q, and here the engine adds a plus sign because the new queen gives check along the eighth rank the instant she appears.
1.e8=Q+
One move ago that was a one point pawn. It is now nine points and giving check.
You can have two queens, or nine
There is no rule that says one queen. Promotion does not depend on what you have already captured or already own, so a player with a queen still on the board may promote to a second, and in theory all eight pawns could arrive.
Over the board, when there is no spare queen in the box, the tradition is an upside-down rook, and in a serious game you should call the arbiter rather than assume your opponent agrees what it is.
Underpromotion, and the two times it is right
Choosing anything other than a queen is called underpromotion. It is rare, it is usually a mistake, and there are exactly two situations where it wins games.
A knight, because a knight checks and a queen does not
Promoting to a knight with check
White to move. A new queen on e8 would attack nothing much and Black's queen would carry on. A knight on e8 checks the king on g7 and attacks the queen on c7 at the same time, and after the king steps away the knight takes her.
1.e8=N+ Kf7 2.Nxc7
A knight fork, delivered by a pawn. Everything here was generated by the engine, including the check mark on e8=N.
A rook, because a queen would be stalemate
The queen that throws the win away
This is the trap. Promoting to a queen leaves the black king with no legal move and no check against him, and the engine calls the result exactly what it is.
1.c8=Q
Stalemate. Half a point, from a position that was completely winning one move ago.
The rook that wins
A rook instead. It covers less, which is the point: the black king keeps one square, has to use it, and walks into mate next move.
1.c8=R Ka6 2.Ra8#
Checkmate. The engine confirms it, and confirms that Black's only legal reply to c8=R was the move played.
How to actually win with an extra pawn
Promotion is the reason an extra pawn is worth having in an endgame and worth nothing much in a middlegame full of pieces. Three things decide whether a pawn gets there: whether it is a passed pawn, whether your king can escort it, and whether the defending king can get in front of it. The last one is what the opposition is for.
White to move. The pawn is close. Work out what stops it, and remove that.
Show the answer
30...Nxe4 31.b7 Ne7 32.b8=Q
The line ends with the pattern paying off in material. The position is from a real game on Lichess, rated 833 in their puzzle pool, and it is one of the positions in the Promotion skill in the trainer.
Questions people ask
Can a pawn become a queen?
Yes, and it usually should. A pawn that reaches the far rank is replaced immediately by a queen, rook, bishop or knight of your colour, and the queen is right in about ninety nine per cent of positions because she is worth the most.
Can you have two queens in chess?
Yes. There is no limit in the rules. Promoting while you still have your original queen is entirely legal, and in theory a player could finish with nine queens. If there is no second queen in the set, an upside-down rook is the usual stand-in.
Can a pawn promote to a king?
No. The choice is queen, rook, bishop or knight. You also cannot decline and leave the pawn where it is: reaching the last rank forces the promotion as part of the move.
Why would you ever promote to a knight?
Because a knight moves in a way a queen cannot. If a new knight gives check, or forks the king and the queen, it can win material that a queen on the same square would not touch. The other reason to underpromote is to avoid stalemate, where a rook wins and a queen only draws.
Does a promoted pawn move immediately?
No. The promotion happens as part of the pawn's move, so the new piece appears and your turn ends. It moves for the first time on your next turn, assuming it survives that long.
Related
Promotion sits under The special moves in the reference. Nearby: