Chess timer › How a chess clock works
How Does a Chess Clock Work?
A chess clock is two timers in one device, and only one runs at a time. While you think, your timer counts down. When you press your button, yours stops and your opponent’s starts, so both players get the same total thinking time.
A game, step by step
- Set the same starting time on both sides, plus any increment or delay.
- Start the clock of the player with the White pieces.
- White makes a move, then presses their side to start Black’s clock.
- Play alternates this way until checkmate, a draw, a resignation or someone runs out of time.
What is the clock for in chess?
It keeps games fair and finite. Without a limit, a player could think for hours, or stall to avoid losing. A clock also makes quick formats such as blitz possible, where the time pressure is part of the challenge.
What happens when time runs out?
When a player’s time reaches zero, they lose on time, which players call a flag fall. The exception is when the opponent cannot checkmate by any legal sequence of moves, for example with only a king left. In that case the game is a draw. Online, the server ends the game automatically. Over the board, the opponent usually has to point out the fallen flag.
Habits of good clock handling
- Press the clock with the same hand that made the move, as standard rules require.
- Do not hover over the button or slam it.
- Press only after your move is complete, including captures and promotions.
- If you are unsure about a clock issue in a tournament, stop and call the arbiter.
Where the chess clock came from
Early players used sand glasses to limit thinking time. Mechanical chess clocks appeared at the London 1883 tournament. Later digital clocks added increments, and Bobby Fischer patented a clock with a bonus after each move in the late 1980s. Digital clocks, and now online ones, replaced analog clocks with flags.
Try it
Use the free online chess timer, or read the time controls guide to choose your settings.