The threefold repetition rule
If the same position appears three times with the same player to move, either player may claim a draw. The catch is what "the same position" means, and it is stricter than the pieces standing on the same squares.
- Three occurrences
- Same side to move
- Five is automatic
The rule is about positions, not moves. If a position that has occurred twice before is about to occur again, or has just occurred, the player to move may claim a draw. The three occurrences do not have to be consecutive and they can be spread across the whole game.
Four things have to match
- Every piece on the same square. Obvious, and the only part most players check.
- The same player to move. A position with White to move is a different position from the same one with Black to move.
- The same castling rights. If either side has lost the right to castle in between, the position is not a repetition, even though the board looks identical.
- The same en passant possibility. If a pawn could have been captured en passant the first time and cannot now, those are different positions.
The last two are why a position can look repeated and not be. They are also why the engine that generated this page writes the castling rights and the en passant square into every position it stores: two boards that look the same are only the same position if those match too.
Seeing it happen
A repetition in four moves
Both players develop a knight and put it straight back. After four half moves the board is exactly as it started, White is to move again, and nobody has lost a castling right or created an en passant square. That is the starting position for the second time.
1.Nf3 Nf6 2.Ng1 Ng8
Identical to the position before the first move, right down to the castling rights. Repeat the manoeuvre once more and either player can claim the draw.
How to claim it
Over the board, you do not just stop playing. You either write down the move that would create the third occurrence and claim without playing it, or you claim immediately after your opponent has created it. Then you stop the clock and call the arbiter, who checks the score sheets. If your claim is wrong you usually lose time as a penalty, so be sure.
Online this is all done for you, and most sites will simply declare the draw or offer you a button.
Five times and it is automatic
Since 2014 the laws also contain a five-fold repetition rule: if the same position occurs five times, the game is drawn immediately whether anyone claims or not. It exists so that an arbiter can end a game that is obviously going nowhere without waiting for a player to do the paperwork.
Why it matters more than it sounds
Repetition is the mechanism behind most saved games. A player who is losing but has a perpetual check draws by repetition. So does a player who has one piece attacking something that cannot move, and shuffles. It is also how grandmasters agree quick draws without offering one, and how you tell your opponent you think the position is balanced.
One practical note: repeating a position once, early, is a normal way to gain time on the clock and to see whether your opponent is willing to deviate. It commits you to nothing.
Questions people ask
What is the threefold repetition rule?
If the same position occurs three times in a game with the same player to move and the same castling and en passant rights, either player may claim a draw. The occurrences do not need to be consecutive.
Does threefold repetition have to be three moves in a row?
No. The three occurrences can be scattered anywhere in the game. Players commonly reach the same position early, play something else, and return to it much later.
Is threefold repetition automatic?
No, it is a claim, and a game continues if neither player claims. Five occurrences of the same position is automatic and ends the game without a claim. Online platforms handle both for you.
Does the fifty-move counter reset on a repetition?
No, they are independent rules. A repetition does not touch the fifty-move counter, which only resets on a pawn move or a capture.
Related
Threefold repetition sits under How a game ends in the reference. Nearby:
- DrawsAll the ways a chess game ends in half a point
- Perpetual checkChecking forever, on purpose
- Fifty-move ruleFifty moves with nothing happening
- En passantTaking a pawn that ran past yours
- CheckThe king is attacked and you must answer
- CheckmateCheck with no legal reply, and the game is over
- StalemateNo legal move, no check, and it is a draw
- Insufficient materialNobody has enough left to mate