Who starts the clock
The person responsible for the event normally decides clock placement and the start procedure. In an ordinary game, Black starts White's clock after both players are ready. If a player arrives late, the applicable event regulations determine when their time begins and what happens after the default time.
What a press means
A press ends one player's turn and starts the other's. Complete the move before pressing. If a piece is knocked over, restore it on your own time. If the clock is set incorrectly or behaves unexpectedly, pause it and ask the organizer instead of improvising a correction.
Flag fall and claims
Digital clocks show a flag indicator when time expires. Whether that produces a win, draw or another ruling depends on the position and the governing rules. This guide teaches operation, not a substitute for the event's current handbook. Check the regulations supplied by your organizer.
Source for the factual guidance above: FIDE Laws of Chess.
What the clock can and cannot prove
A chess clock records time use and, on some models, a press count. It does not record the board position, whether every move was legal, or why a timer was paused. That distinction matters during a disagreement. Preserve the position and display, then explain only what you observed. In formal play, the FIDE Laws treat clock indications as conclusive unless there is an evident defect, while corrections and replacements are handled by the arbiter. In casual play, adopting the same preserve-first habit prevents arguments based on two incomplete memories.
A calm dispute sequence
If the wrong side is running, a flag indicator appears unexpectedly, or a player believes the setting is wrong, stop both timers. Do not add guessed seconds, clear a move counter, or restart play to see whether the problem repeats. Note whose turn it is, both displayed times, the move number if known, and any visible flag or warning symbol. In an event, call the arbiter and step back from the controls. In a friendly game, agree on the correction before resuming. The aim is to protect shared evidence, not to win a button-pressing contest.
Casual rules worth agreeing in advance
Before an informal game, settle four points: the exact time control, whether takebacks are allowed, what happens after an illegal move, and whether a phone-based clock may be interrupted by calls or notifications. Also decide whether a flag ends the game automatically or prompts a position check. These agreements take less than a minute and prevent tournament assumptions from colliding with house rules. If the game is preparation for an event, copy that event's procedure instead of inventing a relaxed version. Consistent practice makes formal clock behavior far easier under pressure.
For the moment when normal play breaks down, continue with illegal moves and the chess clock.
Common questions
Can a player correct the clock during a tournament game?
A player should not improvise a correction. Pause only as the rules permit, preserve the display and position, and ask the arbiter to handle an incorrect setting, defect, or disputed time.
Does running out of time always mean a loss?
Not in every position. Under FIDE rules, a time loss can instead be a draw when the opponent cannot possibly checkmate by any legal sequence. The governing rules and board position determine the result.
Primary references & further reading
Rules and browser capabilities can change. These links are provided for the current governing or technical source.