What is the difference between Fischer and Bronstein increments?

Fischer adds the full increment to your clock every time you make a move — your clock can gain time if you move faster than the increment. Bronstein only refunds the time you actually used on the move, up to the increment, so your clock never grows beyond the base time.

Does "5|3" mean 5 minutes plus 3-second Fischer increment?

Yes. The notation is base minutes | increment seconds. 5|3 is five minutes base time with a three-second Fischer increment per move.

Will the clock drift if I background the tab?

No. Each frame calculates elapsed time from a Date.now() delta, not by counting ticks, so browser background-tab throttling cannot desync the clock.

Why does tapping my own clock hand the turn to my opponent?

That is the standard convention for physical and digital chess clocks: you press your side of the clock to stop it and start your opponent’s. This tool mirrors that behaviour.

Chess Clock

Two-player chess clock with Fischer increment, Bronstein delay, and classic time controls.

Time control

Base (minutes)

Increment (seconds)

Mode

How to use the Chess Clock

Pick a time control, tap a clock to start your opponent’s clock, and keep tapping to alternate turns.

Pick a preset (Bullet 1|0, Blitz 3|2, Rapid 15|10, etc.) or enter your own base time and increment.
Choose an increment mode: Sudden death (no increment), Fischer (adds increment every move), Bronstein (refunds time used up to the increment), or Simple delay (free delay window at move start).
White starts: tap the White clock to begin. That first press starts Black’s clock, matching standard chess-clock behaviour.
On your turn, make your move and tap your own clock to pass the turn to your opponent. The running clock is highlighted; the paused one fades.
Press Pause if the game is interrupted. Press Reset to restart the clocks with the current time control. When a clock hits zero a flag alert announces the winner on time.

Frequently asked questions

What is the difference between Fischer and Bronstein increments?: Fischer adds the full increment to your clock every time you make a move — your clock can gain time if you move faster than the increment. Bronstein only refunds the time you actually used on the move, up to the increment, so your clock never grows beyond the base time.
Does "5|3" mean 5 minutes plus 3-second Fischer increment?: Yes. The notation is base minutes | increment seconds. 5|3 is five minutes base time with a three-second Fischer increment per move.
Will the clock drift if I background the tab?: No. Each frame calculates elapsed time from a Date.now() delta, not by counting ticks, so browser background-tab throttling cannot desync the clock.
Why does tapping my own clock hand the turn to my opponent?: That is the standard convention for physical and digital chess clocks: you press your side of the clock to stop it and start your opponent’s. This tool mirrors that behaviour.