Threefold repetition - chess draw rule

Threefold repetition

Definition

Threefold repetition is a drawing mechanism in chess. If the same position occurs three times with the same player to move and with the same set of legal moves (including identical castling and en passant rights), a player may claim a draw. The repetitions do not have to occur consecutively.

Key to the rule is that the position is identical in every relevant sense: piece placement, side to move, and all rights that affect legal moves. If any of these differ (for example, if one side has lost the right to castle in one occurrence but not in another), the positions are not considered the same for repetition purposes.

How it is used in play

There are two ways to claim threefold repetition under standard FIDE rules:

• You are about to play a move that would cause the same position to appear for the third time. Before making the move on the board, you write it on your scoresheet, then stop the clock and make your claim.
• You have just made a move that resulted in the same position occurring for the third time. You stop the clock and claim the draw.

Important details:

• The same player must be to move in each of the repeated positions.
• Castling rights must be the same each time. For example, if a rook or king moved (even if it moved back), that may permanently change castling rights and break the identity of positions.
• En passant rights must be the same. If a two-square pawn move has just been played in one occurrence (creating a one-move en passant opportunity) but not in another, the positions are not identical.

Related rule: if the same position occurs five times, the game is automatically a draw without any claim (the “fivefold repetition” rule). Likewise, the 50-move rule requires a claim, while the 75-move rule is automatic. See also Fivefold_repetition and Fifty-move_rule.

Strategic and historical significance

Threefold repetition often arises from perpetual check, where the side with the checking pieces can force the opponent’s king to repeat a defensive dance indefinitely. While “perpetual check” is a common phrase, the draw is actually enforced by the threefold repetition rule (or, less commonly, by the 50/75-move rules). See Perpetual_check.

Strategically, repetition serves several purposes:

• Saving a bad or worse position: the defender can steer into a fortress or a checking sequence that repeats.
• Testing the opponent: players may “repeat once” to gain time on the clock (with increment) or to see if the opponent is willing to deviate and take risks.
• Pragmatism at elite level: if a position is objectively equal, both players might repeat to secure a half-point, particularly near time controls.

Historically, many top games have featured intentional repetitions. A famous storyline from Kasparov vs. Deep Blue (1997) involved a moment where Kasparov expected the computer to allow a repetition; when it declined, it fueled debate about the machine’s decision-making, underscoring how threefold repetition can be a psychological and practical tool as well as a rule.

Examples

Example 1: A minimal demonstration

This short sequence shows the concept clearly. After 4...Ng8, the initial starting position has occurred three times (initial setup, after 2...Ng8, and after 4...Ng8), so White may claim a draw.

Moves: 1. Nf3 Nf6 2. Ng1 Ng8 3. Nf3 Nf6 4. Ng1 Ng8 1/2-1/2

Viewer:

Example 2: Perpetual check leading to repetition

Imagine a simplified middlegame where White’s queen can keep checking Black’s king, forcing it to oscillate between g8 and h7, while Black has no safe square to flee to or interpose. If the sequence returns to the exact same positions (same side to move, same castling/en passant rights), the game can be drawn by threefold repetition. This is common in queen-and-rook vs. king-and-pieces scenarios where the defender’s king is exposed and the attacker lacks a safe way to improve.

Example 3: Not all “look-alike” positions repeat

• Castling rights: Suppose Black once moved the rook on h8 and moved it back. Even if all pieces return to the same squares, Black’s right to castle kingside is gone forever. Positions before and after that rook move are not identical for repetition.
• En passant: If in one occurrence the last move was a two-square pawn advance creating an en passant capture, but in another occurrence no such right exists, the positions are different.
• Side to move: The board may look the same, but if it’s White to move in one snapshot and Black to move in another, they do not count as a repetition of the same position.

Claiming and practical tips

• Know when you can claim: Either just after you have created the third occurrence or immediately before playing the move that would create it (write the move first, then claim).
• Don’t rely on “same moves”: It’s about identical positions and rights, not identical move sequences. Different move orders can still produce a valid threefold repetition.
• Online play: Many servers automatically recognize and allow you to claim when the position qualifies; some may even auto-declare the draw upon the third occurrence.
• Time management: Strong players sometimes “repeat once” to gain increment or reach a time control, then deviate when they’re ready to play for more.

Interesting facts

• Threefold repetition is a claim; fivefold repetition is automatic under modern FIDE rules.
• Perpetual check is not a separate law in current chess rules; it’s typically enforced via threefold repetition.
• In endgames, creating a reliable repeated checking pattern is a key drawing resource, especially when down material.
• Official PGN databases usually annotate such results as “1/2-1/2” with a termination note like “drawn by repetition.”