How it works
Each player has a clock, and only the one whose turn it is runs. A tap on your side ends your turn and starts the next player's. The page records each tap with the time on the clock and works out everyone's time from that list, so a reload, a second tab or an undo always gives the same answer.
With an increment, the extra seconds are added from the first move, so 3+2 starts at 3:02, the way DGT clocks do it. A delay holds your time still for a few seconds each move and shows the delay counting down; Bronstein shows it as one number and gives back what you used, up to the delay. US Chess counts the two as equivalent.
When someone runs out, their side turns red and the clock keeps working: whether that's a loss, a draw or "play on" depends on your rules, and FIDE and US Chess differ. Undo takes back a mistaken tap as if it never happened.
The board is drawn against the phone itself, so it doesn't spin when the phone tilts, and the screen stays on during a game. Everything stays in this browser.
Questions people ask
- How does a chess clock work?
- It's two countdowns, and only one runs at a time: when you finish your move, you press your side and your opponent's time starts. FIDE's Laws call the end of a player's time "flag-fall". Here, the whole half of the screen facing you is the button.
- What does 3+2 mean?
- 3 minutes for each player, plus 2 seconds added for every move. The increment counts from the first move, so a 3+2 clock starts at 3:02, as on DGT clocks.
- What's the difference between increment, delay and Bronstein?
- An increment adds time after every move, so moving fast builds up time. A delay waits a few seconds before your time starts each move, and Bronstein gives back what you used, up to the delay; US Chess calls the two "mathematically equivalent", and neither lets your time grow.
- What happens when a player's time runs out?
- Under FIDE's Laws that player loses, unless the opponent couldn't checkmate by any series of legal moves, which makes it a draw; US Chess lists specific cases instead. This clock shows who ran out and keeps counting; the result is for you and your rules to decide.
- Can we use it for board games with more players?
- Yes, for 2 to 8 players, with a time bank each, a limit per turn, or a simple count of each player's time. Lay the phone in the middle: each seat faces its player, the center turns to whoever's turn it is, and a tap anywhere passes the turn.
Sources
- FIDE Laws of Chess (from 1 January 2023)
- FIDE: 2025 Women's World Championship match time control
- FIDE World Rapid and Blitz Championships 2025
- US Chess Rules of Chess, chapter 1
- US Chess: Just the Rules, rulebook updates 2021–22 (simple and Bronstein delay)
- DGT 2010 manual (Fischer, Bronstein and byo-yomi definitions)
- Lichess FAQ: how time controls are categorized
- Chess.com: chess time controls
- WHATWG HTML: activation-triggering input events
- MDN browser data: ScreenOrientation.angle