A chess clock looks like a simple device, but the rules governing how you use it are precise — and in a rated game, getting them wrong can cost you a point. Here is a complete rundown of the rules as they stand under the FIDE Laws of Chess, with the practical detail that beginners and club players most often miss.
The basic duty: press after every move
Every time you complete a move, you must press your clock button. This is not optional. Pressing transfers the time obligation to your opponent and records the move as completed. Until you press, your clock is still running and the move is not officially done.
The FIDE Laws state the requirement plainly: a move is not complete until the player has pressed the clock. So if you release a piece on a square but have not yet pressed, you have not finished your move — your clock is ticking, and you can still change your mind if you have not let go.
Same hand for move and press
You must press the clock with the same hand you used to move the piece. This rule exists to prevent a player from hovering a hand over the clock button while still reaching across the board with the other — a tactic that shaves fractions of a second in bullet and blitz.
If you move with your right hand, press with your right hand. In practice, referees rarely intervene unless the habit is persistent and deliberate, but in a serious game it is worth doing correctly from the start.
Do not hover over the button
You are not allowed to keep a finger resting on or over the clock button. You may not hold the clock down. Between moves your hands should be away from the device. This prevents players from making the press as instantaneous as possible by barely lifting a finger — again, mainly relevant in bullet where every tenth of a second counts.
Complete the move before pressing
The press must come after the move is fully completed on the board. If you move a piece and press before letting go, the move is not considered complete. If you accidentally press while still holding the piece, pick it up, complete the move properly, then press again.
For castling, the king must be moved to its final square before you press. For promotion, the promoted piece must be placed on the board before the clock is pressed — choosing a piece from outside the game and then pressing is not permitted.
Touching pieces
The touch-move rule and the clock rules work together. If you touch a piece, you must move it (if a legal move exists). If you touch an opponent’s piece, you must capture it (if a legal capture exists). The clock rule stacks on top: once you have completed that move, you must press.
Touching a piece without releasing it is not a completed move, so you cannot press the clock in that state. Only when the piece is on its destination square and your hand is clear can you press.
Flag fall and losing on time
When your clock reaches zero, your flag falls. In a digital clock this is usually a sound and a display of 0:00. You lose the game on time — unless your opponent does not have sufficient mating material. If the opponent has only a king and cannot possibly checkmate you by any legal sequence of moves, the game is drawn rather than lost.
In a sudden-death finish — no increment, no extra time periods — if it is genuinely impossible to tell which flag fell first, the game is drawn. In practice, digital clocks make this unambiguous: the side shown as zero loses.
Both flags down
If both players run out of time in the same move, the result depends on what can be proved. If the arbiter or both players agree that both clocks reached zero and neither can show whose went first, the game is drawn. In increment games this is rare because the increment is added before zero can be reached simultaneously — but in bullet with no increment it does occasionally happen.
Illegal moves
If you make an illegal move and your opponent points it out before making their own move, the illegal move is retracted and you must make a legal move with the same piece if possible. In rated games under current FIDE rules, making two illegal moves in the same game results in a loss.
The clock consequence: if you press the clock after an illegal move and your opponent notices, they can claim. The position is restored, you retract the move, and your clock continues from where it was when the illegality is addressed. Time lost in the dispute is usually absorbed; the arbiter uses judgement.
Who decides where the clock goes?
In a rated game, the arbiter places the clock. In the absence of an arbiter, the player with the Black pieces chooses which side the clock sits on. By convention this is usually the right side of the player with White — but the Black player can put it on the left if they prefer.
Starting the clock
Before the game starts, neither player’s clock should be running. The convention — and FIDE rule — is that White’s clock is started by Black at the beginning of the game. In practice at club level, someone just presses to get going; what matters is that White’s clock is the one running when the first move has not yet been made.
If White is not present at the board when the round starts, their clock runs from the scheduled start time. In most tournaments there is a grace period — typically 60 minutes for standard play, often less for blitz — after which the absent player forfeits.
Claiming a win on time
You cannot claim a flag fall after you have made your own move. If your opponent’s time expires but you press your button before noticing, the game continues. You must make the claim while your opponent’s clock is running, or immediately when you notice the flag has fallen and before you press your own clock.
In a game without an arbiter, a player who runs out of time and acknowledges it has effectively conceded the game. Disputes go to the arbiter; without one, good faith is expected.
Stopping the clock
You may stop the clock — press both buttons so neither is running — to summon the arbiter. Do not stop the clock for any other reason during play. If there is a problem with the board, a piece knocked over, an illegal position discovered, stop the clock and call the arbiter rather than trying to fix things yourself.
Practising the rules
The best way to internalise clock rules is to play. The online clock covers every time control from bullet to classical and reflects the same press-after-move rhythm you will use over the board. Start with blitz — fast enough to feel the pressure, slow enough to keep good habits — and the rules will become automatic long before you sit down at a rated board.