How does a chess clock work?
A chess clock is really two clocks that can never run at the same time. Each player has their own budget of thinking time, and only the player to move is spending it. When you have made your move on the board, you tap your own side — that stops your clock and starts your opponent's. Whoever exhausts their time first loses on time, an outcome still called flag-fall after the small mechanical flag that the minute hand lifted and dropped on analog clocks.
Set the minutes and increment before you begin, or use one of the presets. The top half of the display is rotated 180° so two players sitting opposite each other can share a single phone or tablet laid flat between them, each reading their own clock the right way up.
Time controls explained
A time control is written as minutes + increment. "3+2" means each player starts with three minutes and receives two extra seconds after every move they complete. The increment — named after Bobby Fischer, who patented the idea in 1988 — exists to solve a real problem: without it, a player with a completely winning position can still lose simply by running out of seconds while moving pieces. An increment guarantees you can always keep playing, and it makes the endgame about chess rather than about mouse speed.
- Bullet (1+0, 2+1) — one or two minutes for the entire game. Pattern recognition and hand speed dominate; deep calculation is impossible.
- Blitz (3+2, 5+0) — the most popular online format. Long enough for real ideas, short enough to play a dozen games in an evening.
- Rapid (10+5, 15+10) — you can actually calculate variations. This is the usual format for club evenings and online tournaments.
- Classical (60+30, 90+30) — the format of serious over-the-board tournaments, where games can run several hours.
FIDE, the international chess federation, draws the official lines by total expected game length rather than by starting minutes alone, but the categories above are how almost everyone uses the terms in practice.
Etiquette and common mistakes
- Move first, then press. Pressing the clock before completing your move is the classic beginner error. Your move is only finished when the piece is released.
- Use the same hand for both. In tournament play you must move the piece and press the clock with the same hand — using two is an illegal, and rather cheeky, way to save time.
- Press firmly, once. Repeatedly tapping or slamming does nothing except annoy your opponent, and in a rated game it can be penalised.
- If you forget to press, that is your problem. Your opponent is under no obligation to remind you, and your clock keeps running.
Not just for chess
Any two-player game with alternating turns benefits from a shared clock, and plenty of them are much better for it. Go and shogi have used clocks for as long as chess has. Scrabble tournaments run on them. Backgammon, draughts and two-player card games all become noticeably brisker when a clock is watching. Outside games entirely, the same mechanism works well for timed debate rounds, structured interviews where each side gets equal airtime, and negotiation practice — anywhere the point is that two parties get exactly the same budget.
Frequently Asked Questions
Why is the top side upside down?
So two people facing each other can share one device. Put the phone or tablet flat between you and each player reads their own clock upright.
Which side do I tap?
Your own, after you have made your move. Tapping your side ends your turn and starts your opponent's clock.
What does the increment do?
It adds the configured number of seconds to your clock each time you complete a move, so you can never be reduced to zero purely by the mechanics of moving. Set it to 0 for a sudden-death control.
Which time control should I choose?
5+0 or 3+2 for a quick casual game, 10+5 if you want time to think, 15+10 or longer for a serious game. If you are new to playing with a clock, start at 10+5 — bullet with no increment is unforgiving.
Can I pause the game?
Yes, the Pause button stops both clocks. Reset returns both sides to the starting time and clears the move counters.
Does it count moves?
Yes, each side shows how many moves that player has made, which is useful for time controls that add time after a set number of moves.
What happens when a clock hits zero?
That side is out of time — the flag has fallen — and under standard rules that player loses, unless their opponent has insufficient material to deliver checkmate.
Related tools
For single-player timing use the stopwatch or the timer. If you need a steady beat rather than a clock, try the metronome.