Chess Clock
A two-player game clock for a phone or laptop: increments, delays and stages.
Press your own clock when you have made your move. Keys, while a clock is selected or in full screen: Space presses the running clock, A presses Player 1’s clock and L Player 2’s, P pauses.
Settings
These settings apply to the next game.
About the Chess Clock
A full-screen game clock for two players. Put your phone between you (the top clock turns to face the other player) or use a laptop, choose a time control and press your own clock after each move, as on a real chess clock. It covers the time controls used in clubs and tournaments: Fischer increment (5 + 3), Bronstein and simple delay (US Chess style, G/90; d5), multi-stage controls such as 90 minutes for 40 moves then 30 minutes with 30 seconds a move, byo-yomi for Go and an hourglass mode.
The clock counts from timestamps, so it stays exact in a background tab and on a locked phone. It counts each player’s moves, shows tenths of a second in the last 10 seconds, clicks on each press, beeps at 10 seconds and sounds an alarm when a flag falls, keeps the screen on while a game runs, and remembers your settings. Nothing is uploaded.
How to use it
- Choose a time control in Settings below the clocks, or build your own with up to three stages, an increment or a delay, byo-yomi periods and different times for the two players.
- Put the device between the players. The bottom (or left) clock is Player 1’s, normally White; on a phone held upright the top clock turns to face its player.
- To start, Player 2 (Black) presses their own clock: Player 1’s clock starts. After each move, press your own clock to start your opponent’s.
- Pause stops both clocks (key P) and Reset sets up a new game. While paused you can correct either clock, for example to add 2 minutes after an illegal move.
- Use Full screen to show only the clocks. With a keyboard, select a clock (Tab) or use Full screen: then Space presses the running clock, A presses Player 1’s clock (bottom or left) and L Player 2’s, and P pauses.
Examples
5 min + 3 s
Each player starts with 5:00; a move that takes 10 seconds leaves 4:53.
G/30; d5 — 30 min, 5 s delay
A move made within 5 seconds costs nothing; a 12-second move costs 7 seconds.
5 min, 3 s Bronstein delay
A 2-second move costs nothing (the 2 seconds come back); a 10-second move costs 7 seconds.
90 min for 40 moves, then 30 min, + 30 s from move 1
After their 40th move each player gets 30 more minutes, and every move adds 30 seconds.
10 min + 5 × 30 s
After the main time every move must be made within 30 seconds; a period that runs out is used up, and running out of the fifth ends the game.
Common uses
- Blitz and rapid games with friends, at a club or in a school chess session, without a physical clock.
- Practising tournament time controls with increments, delays and a second time control after move 40.
- Go, shogi and other board games with byo-yomi, and any two-player game where each side should get equal thinking time.
- Giving a weaker player more time (time odds), or keeping a long game going across a break with Pause.
Increment, delay and the other modes
- Fischer increment, named after Bobby Fischer: a fixed time is added after every move you complete, so you can build up time with quick moves.
- Bronstein delay: after each move you get back the time you used, up to the delay. You never end a move with more time than you started it with.
- Simple delay (US delay): each turn the clock waits for the delay before your own time starts to run, so a move within the delay costs nothing. This is the “time delay” mode of the FIDE Laws of Chess.
- Several stages: each stage adds its time once you complete its moves (for example 30 minutes after move 40), and its own increment applies during it.
- Hourglass: the time you use is added to your opponent’s, like a sand timer turned over.
- Byo-yomi (Japanese, used in Go): after the main time each move must be made within one period. Moving in time keeps the period; letting it run out uses it up, and the game is lost when the last one runs out.
Playing by the rules
Under the FIDE Laws of Chess (Article 6), the clock of the player with the white pieces is started at the beginning of the game, each player stops their own clock with the same hand that made the move, and a player whose flag falls loses, unless the opponent cannot checkmate by any series of legal moves, which makes it a draw. This clock shows when a flag falls but does not know the position: decide such cases yourselves, or ask the arbiter.
In casual games the player with the black pieces usually presses their clock to start White’s, which is how this clock starts.
Limitations
- Phones can sleep during long thinks: Keep the screen on asks the browser for a screen wake lock while a game runs, but battery savers can refuse it. The times stay correct anyway, because the clock counts from timestamps.
- Sound plays after the first tap on the page, and not while the device is muted.
- Canadian overtime, tournament penalties and move-count checks are not included, and the clock does not know the position on the board.
- If the page is reloaded during a game, the clock comes back paused at the moment it was left.
Privacy
Everything runs in your browser and nothing is uploaded. Your settings (with the player names) and a game in progress are kept in this browser’s storage on this device only, so a reload brings them back.
Frequently asked questions
How does a chess clock work?
Each player has their own clock and only one runs at a time. When you have made your move you press your clock: it stops and your opponent’s starts. If your time reaches zero your flag falls, and you usually lose on time.
What does 5 + 3 mean?
Five minutes for each player, plus a 3-second increment added after every move. Choose 5 min + 3 s in Settings.
What is the difference between increment and delay?
An increment (Fischer) is added after every move, so quick moves build up time. A delay never adds time: with a simple delay the clock waits before your time starts, and with a Bronstein delay you get back what you used, up to the delay.
Who starts the chess clock?
White’s clock runs first. In tournaments the arbiter starts it; in casual games the player with the black pieces presses their clock to start White’s, as here.
Can I give one player more time?
Yes. In Settings, choose Custom, tick Different times for the players and enter Player 2’s time — a common way to give a stronger player time odds.
Does it work offline?
Yes. Once the page has loaded it needs no connection, and nothing you do on it is sent anywhere.