How to use the chess clock
Choose a time control from the menu — the numbers mean minutes + seconds of increment, so 3 + 2 is three minutes each with two seconds added after every move. Put the device next to the board with each half nearest its player. On a phone held upright the two halves stack and the top one is rotated to face the player opposite, exactly like a dedicated chess clock app; turn the phone sideways and they sit side by side.
As in over-the-board play, Black starts the clock: Black taps their own side (or presses Space) and White's time begins. From then on, after making your move, tap your own side. Your clock stops, any increment is added, and your opponent's clock starts. Taps on the side that isn't running are ignored, so a nervous double-tap can't hand your opponent a free move.
The centre buttons pause and reset. While paused, small −10 s / +10 s / +1 min buttons appear for each player, for the times an arbiter awards extra time after an illegal move or a clock was started late. F or the Full screen button fills the screen, and the screen is kept awake while a game is running.
Increment, Bronstein and simple delay explained
A plain "sudden death" clock lets a game be lost on time with a winning position and a flurry of pre-moves. Modern time controls avoid that in one of three ways, all of which this clock supports:
| Mode | What happens on each move | Used by |
|---|---|---|
| Fischer increment | A fixed number of seconds is added after you press, however long you took. Time can build up above the starting amount. | FIDE, online chess (3+2, 15+10) |
| Bronstein delay | After you press, you get back the time you used, up to the delay. A fast move is refunded in full; you can never end a move with more time than you started it with. | Some national federations, older DGT settings |
| Simple (US) delay | Your clock waits for the delay before it starts counting down. A "delay" counter shows the seconds left before your main time moves. | US Chess (e.g. G/30 d5) |
| None | Sudden death: each player's time only ever goes down. | Casual blitz, 1+0 bullet |
Bronstein and simple delay give the same result on any single move — both protect the delay period — but they feel different: with simple delay the display stays still at first; with Bronstein it ticks down and then jumps back. Choose whichever your event specifies.
Presets, time odds and multi-stage controls
The menu includes the common online and club controls: 1+0 and 2+1 bullet, 3+0, 3+2, 5+0 and 5+3 blitz, 10+0, 10+5, 15+10, 25+10 and 30+0 rapid, 90+30 classical, and the full FIDE classical control: 90 minutes for the first 40 moves, then 30 more minutes, with 30 seconds added from move one. There is also a US-style 5 minutes with 5 seconds delay, and a Bronstein blitz setting.
Open Settings for anything else. Untick Same time for both to give players different times — a popular way to level a game between a strong and a weaker player, for example 3 minutes against 10. The extra time control fields add minutes to a player's clock when they complete a given number of moves, which is how multi-period classical controls work. You can also change the low-time warning threshold and turn the per-second ticks under ten seconds on or off. Settings are remembered in your browser for next time.
The clock works for more than chess: Go, Scrabble, shogi and any two-player board game with a turn timer. If you just need to time a whole session, use the stopwatch; for a fixed countdown, the online timer.
Low time, flag fall and what the rules say
When a player drops below the warning threshold (10 seconds by default), their side turns amber, gets a Low time label and gives a double beep, and under ten seconds the display shows tenths and can tick every second. When a clock reaches zero, that side turns red and shows Flag, both clocks stop, and a flag alarm sounds. The flag is detected from timestamps, so it is right to the tenth even if a tab was in the background.
Under FIDE Laws of Chess (article 6.9), a player whose flag falls loses — unless the opponent cannot checkmate by any series of legal moves, in which case the game is drawn. A lone king, or king and bishop or king and knight, cannot win on time. In casual games with no arbiter, the player with time left should claim the win.
Timing is fair to both players: each press is timed from the moment your finger touched the screen or the key went down, not from when the browser finished processing the tap. Everything runs locally, with no account and no connection needed once the page has loaded. Count captured points or game scores with the tally counter.
Frequently asked questions
Who starts the chess clock, White or Black?
Black. Under the rules of over-the-board chess, the player with the black pieces starts White's clock at the beginning of the game. On this clock, Black taps their own side, or anyone presses Space, and White's time begins running. After that, each player taps their own side straight after making a move.
What does 3+2 or 15+10 mean?
The first number is each player's starting time in minutes and the second is the increment in seconds added after every move. So 3+2 gives both players three minutes, and each move adds two seconds. 15+10 is fifteen minutes with ten seconds added per move, a common online rapid control.
What is the difference between increment and delay?
An increment adds a fixed number of seconds after every move, so a player's time can grow. A delay protects a few seconds of each move instead: with simple delay the clock waits before counting down, and with Bronstein delay you get back the time you used, up to the delay. Delay modes never give you more time than you started the move with.
Can I give players different amounts of time?
Yes. Open Settings, untick Same time for both, and enter separate hours, minutes and seconds for White and Black. This is called time odds and is a good way to balance a game between players of different strength. The increment or delay applies to both players.
Does the chess clock work on a phone lying flat on the table?
Yes. In portrait the two clocks stack, with the top half rotated to face the player opposite; in landscape they sit side by side. Tap zones fill the screen, react on touch-down rather than on release, ignore the clock that isn't running, and the screen is kept awake during a game in browsers that support it.
What happens if I reload the page in the middle of a game?
The game comes back paused, with each player's remaining time and move count as they were when the page closed. Resume with the pause button or Space. Your chosen time control, sound setting and warning threshold are also remembered, all stored only in your browser.