Chess Clock

How a chess clock works

A chess clock is really two countdown clocks joined together, but only one ever runs at a time. Each player has their own bank of time. On your move you think and play while your clock ticks down, then you tap your own side to stop your clock and start your opponent's. The two clocks never run at once, so the total time spent is split exactly the way the game was played.

If your clock reaches zero before the game ends, you have “flagged” — you lose on time regardless of the position on the board (unless your opponent has no way to checkmate, in which case it is usually a draw). That pressure is the whole point: a clock turns chess into a test of decision-making speed as well as skill. This timer uses a precise timestamp-based tick, so the time you see stays accurate even if your device is busy or the tab is throttled.

Fischer increment and delay explained

Plain time controls have a flaw: in a scramble you can lose on time even when you are about to win, simply because you cannot move the pieces and press the clock fast enough. Two systems fix this.

• • Fischer increment (the system this clock uses): after every move you complete, a fixed number of seconds is addedto your remaining time. A “5+3” control means five minutes to start plus three seconds back per move. Play quickly and your time can actually grow.
• • Bronstein / simple delay: your clock pauses for a set number of seconds at the start of your turn before it begins counting down. You never gain time, but you always have a small buffer to make a move. Increment is more common online; delay is popular in over-the-board tournaments.

The notation you see online — like 3+2 — is always written as base minutes plus increment seconds.

Common time controls: bullet, blitz, rapid and classical

These same presets work for far more than chess — use them for Scrabble, Go, debate rounds, two-player board games, or any turn-based activity where each side gets a fair share of time.

Frequently asked questions