The following rules are the rules used for "over the board" (OTB) games. They are defined by the FIDE Laws of Chess. The FIDE Laws of Chess define the rules for Standard chess, Rapid chess, Blitz chess and guidelines for Chess960. For Standard chess, the players must record the moves, which is optional in Rapid chess and Blitz Chess. Some rules are specifically adapted for disabled players. As the rules cover OTB play, they cannot be directly applied to computer chess or online chess, played on a computer device. The rules for correspondence chess are defined by the ICCF.
Moving the pieces
The movement of pieces is to be done with one hand. Once the hand is taken off a piece after moving it, the move cannot be retracted unless the move is illegal. As for the touch-move rule, an arbiter who observes a violation of this rule must intervene immediately. A player must claim a violation of the rule immediately before making a move, or lose the right to claim. When castling, a player should first move the king with one hand and then move the rook with the same hand. In the case of a pawn promotion, if a player releases the pawn on the eighth rank, the player must promote the pawn. After the pawn has moved, the player may touch any piece not on the board and the promotion is not finalized until the new piece is released on the promotion square
In serious play, if a player having the move touches a piece as if having the intention of moving it, then the player must move it if it can be legally moved. So long as the hand has not left the piece on a new square, any legal move can be made with the piece. If a player touches one of the opponent's pieces then that piece must be captured if there is a legal move that does so. If none of the touched pieces can be moved or captured there is no penalty. An arbiter who observes a violation of this rule must intervene immediately. A player must claim a violation of the rule immediately before making a move, or lose the right to claim. When castling, the king must be the first piece touched. If the player touches the king and a rook, the player must castle with that rook if it is legal to do so. If the player completes a two-square king move without touching a rook, the player must move the correct rook accordingly if castling in that direction is legal. If a player starts to castle illegally, another legal king move must be made if possible, including castling with the other rook. If a player moves a pawn to its eighth rank, it cannot be substituted for a different move of the pawn when the player has stopped touching it. However, the move is not complete until the promoted piece is released on that square. If a player wishes to touch a piece with the intention of adjusting its position on a square, the player must first alert the opponent of this intention by saying J'adoube or "I adjust". Once the game has started, only the player with the move may touch the pieces on the board.
Tournament games are played under time constraints, called time controls, using a chess clock. Each player is timed separately and must make moves within the time control or forfeit the game. There are different types of time controls applied. For standard chess, different periods can be defined with different fixed times (e.g. first 40 moves in 100 minutes, next 20 moves in 50 minutes, remaining moves in 15 minutes). For rapid and blitz chess, only one period can be defined where all moves must be performed. Additionally, an increment or delay per move may be defined.
- When a player runs out of time, this event is called flag fall. A flag fall has no consequences unless stated as observed by the arbiter, in which case the arbiter must intervene, or claimed by a player.
- When no flag fall is stated, and one of the following events occur, the result of the game still holds. It is of no relevance if the player runs out of time afterwards, or has already run out of time, but this was not stated:
- If a move results in a stalemate, dead position, fivefold repetition or the seventy-five-move rule applies, the game is over and the game is drawn.
- If a player correctly claims flag fall, that player wins. But if the claiming player is out of time, or could not still theoretically checkmate the opponent, the game is a draw.
The United States Chess Federation (USCF) rule is different. USCF Rule 14E defines "insufficient material to win on time", that is lone king, king plus knight, king plus bishop, and king plus two knights opposed by no pawns, and there is no forced win in the final position. Hence to win on time with this material, the USCF rule requires that a win can be forced from that position, while the FIDE rule merely requires a win to be possible.
- With mechanical clocks only, flag fall for both players can occur. With digital clocks, the clock indicates which flag fell first, and this information is valid.
- If a flag fall is stated, and as can happen with mechanical clocks only, the flag fall happened for both players.
- If it can be established which player ran out of time first, the rules apply for flag fall for one player only.
- Otherwise, the result is a draw, unless this is a standard chess game which is not in the last period, here the play will be resumed.
In the last period of a standard chess game or rapid games, if played without increment, a special set of rules applies regarding the clock, referenced as "Quickplay Finishes". These rules allow a player with under two minutes time to request an increment introduced, or request a draw based on claiming no progress or no effort, to be ruled by the arbiter. These rules have been relevant when playing with mechanical clocks, which do not allow setting an increment and are today with digital clocks of second importance only, as playing with increment is recommended.
Each square of the chessboard is identified with a unique pair of a letter and a number. The vertical files are labeled a through h, from White's left (i.e. the queenside) to White's right. Similarly, the horizontal ranks are numbered from 1 to 8, starting from the one nearest White's side of the board. Each square of the board, then, is uniquely identified by its file letter and rank number. The white king, for example, starts the game on square e1. The black knight on b8 can move to a6 or c6. In formal competition, each player is obliged to record each move as it is played in a chess notation in order to settle disputes about illegal positions, overstepping time control, and making claims of draws by the fifty-move rule or repetition of position. Algebraic chess notation is the accepted standard for recording games today. There are other systems such as ICCF numeric notation for international correspondence chess and the obsolete descriptive chess notation. The current rule is that a move must be made on the board before it is written on paper or recorded with an electronic device. Both players should indicate offers of a draw by writing "=" at that move on their score sheets. Notations about the time on the clocks can be made. A player with less than five minutes left to complete all the remaining moves is not required to record the moves (unless a delay of at least thirty seconds per move is being used). The score sheet must be made available to the arbiter at all times. A player may respond to an opponent's move before writing it down.
An illegal move is a piece not moving according to its possible defined movements, moving according to its possible movements but exposing its own king to check or leaving the own king in check. Some movements contain requirements to the position to be legal (castling, en passant and promotion). Further pressing the clock without making a move and making a move with two hands is considered and penalized as if an illegal move. A player who makes an illegal move must retract that move and make a legal move. That move must be made with the same piece if possible, because the touch-move rule applies. If the illegal move was an attempt to castle, the touch-move rule applies to the king but not to the rook. If the mistake is noticed, the game should be restarted from the position in which the error occurred. The arbiter should adjust the time on the clock according to the best evidence. Some regional organizations have different rules. A player may correct an illegal move if the player has not pressed the clock. If a player has pressed the clock, the illegal move may be stated by the arbiter intervening or by the opponent claiming the illegal move. In Standard chess, the illegal move must be claimed before the end of the game. In the most used form of Rapid chess and Blitz chess, if the arbiter does not intervene and the opponent moves, the illegal move is accepted and without penalty. According to the FIDE Laws of Chess, the first stated completed illegal move results in a time penalty. The time penalty consists of giving the opponent two minutes extra time in standard and rapid chess, one minute extra time in Blitz. The second stated completed illegal move by the same player results in the loss of the game, unless the position is such that it is impossible for the opponent to win by any series of legal moves (e.g. if the opponent has a bare king) in which case the game is drawn. A move is completed when it has been made and the player has pressed the clock.
For Standard chess and the most used form of Rapid and Blitz chess there are the following rules. If it is discovered during the game that the starting position was incorrect, the game is restarted. If it is discovered during the game that the board is oriented incorrectly, the game is continued with the pieces transferred to a correctly oriented board. If the game starts with colours reversed, the game is restarted if less than 10 moves have been made by both players, otherwise the game is continued. If the clock setting is found to be incorrect during the game, it is corrected according to best judgement. Some regional organizations have different rules.
If a player knocks over pieces, it is the same player's responsibility to restore them to their correct positions, on that player's time. If it is discovered that an illegal move has been made, or that pieces have been displaced, the game is restored to the position before the irregularity. If that position cannot be determined, the game is restored to the last known correct position.
An illegal position is a position which cannot be reached by any series of legal moves.
Players may not use any notes, outside sources of information (including computers), or advice from other people. Analysis on another board is not permitted. Scoresheets are to record objective facts about the game only, such as time on the clock or draw offers. Players may not leave the competition area without permission of the arbiter. High standards of etiquette and ethics are expected. Players should shake hands before and after the game. Generally a player should not speak during the game, except to offer a draw, resign, or to call attention to an irregularity. An announcement of "check" is commonly made in informal games but is not recommended in officially sanctioned games. A player may not distract or annoy another player by any means, including repeatedly offering a draw. Due to increasing concerns about the use of chess engines and outside communication, mobile phone usage is banned. The first forfeit by a high-profile player, for phone ringing during play, occurred in 2003. In 2014 FIDE extended this to ban all mobile phones from the playing area during chess competitions, under penalty of forfeiture of the game or even expulsion from the tournament. The rules allow for less rigid enforcement in minor events.