Chess Clock
A real two-sided chess clock with increment, both delay styles and multi-period tournament controls. Tap your own side to end your move.
Tap your own clock to end your move · Space also presses · P pauses
Increment, delay, and the difference
- Increment adds time after every move, so a fast player banks it and the game can always be finished. Delay does not: whatever you do not use is gone.
- Simple delay and Bronstein delay leave you with exactly the same time after a move. They differ only in what the display does while you are thinking — one holds the clock still, the other runs it and gives the time back.
- A clock that has run out is not automatically a loss. If the other side has no way to force mate with what they have left, it is a draw.
- Press the clock with the same hand you moved with. It is a rule, not an etiquette, and it is the one people get pulled up on.
- Increment can be banked. Play twenty quick moves on a 3+2 clock and you will have more time than you started with. Delay can never do that — whatever you do not use is simply gone.
- In a two-period control the periods are per player. Reaching move 40 adds the second period to your clock, not to both.
How to use
- Pick a time control and put the phone between you.
- Black presses to start White’s clock, as on a real clock.
- Each player taps their own side to end their move.
Frequently asked questions
What is the difference between increment and delay?
Increment adds time after every move, so a fast player banks it and the clock can climb above where it started. Delay only gives you a few seconds before your clock begins moving, and anything you do not use is lost — you can never finish a move with more time than you began it with.
Simple delay or Bronstein — which should I pick?
It makes no difference to the result, which surprises most people. They leave you with exactly the same time after a move; they differ only in what the display does while you think. Simple delay counts the delay down and holds the main clock still, Bronstein runs the main clock and gives back what you used, up to the delay.
How does a two-period control work?
Reach the required move count and the next period’s time is added to your clock automatically, and your move count restarts. The periods are per player, so you get your extra thirty minutes when you reach move 40, whatever your opponent has done.
Does running out of time always lose?
No. If the player who still has time has no way to force mate with the pieces left on the board, the game is a draw. It is the rule people are most often surprised by after losing on time.
Which hand should press the clock?
The one you moved with. It is an actual rule rather than etiquette, and it is the one players get pulled up on in their first tournament.
Does the clock keep running if I lock the phone?
It uses the real elapsed time between frames, so a brief interruption is caught up rather than lost. But a phone that suspends the page entirely will pause — put it face up and leave it alone.
🔒 This tool runs entirely in your browser. Nothing you enter is uploaded, logged, or stored.