Chess Clock

About the chess clock

A chess clock is really two clocks that never run at the same time: when one player's clock is counting down, the other's is paused. After you move, you press your side and your opponent's clock starts. The first player whose time reaches zero loses (a "flag fall"), unless their opponent has no way to deliver checkmate. This digital clock reproduces that mechanism with one-tap switching and the standard tournament presets, so you can play timed games without buying hardware.

The notation you will see, such as 5+0 or 3+2, is shorthand for the time control: the first number is the base minutes each player gets, and the second is the increment in seconds added back after every move. So 3+2 means three minutes plus two seconds per move. Time controls split games into recognised speeds: bullet, blitz, rapid, and classical, each with its own feel and its own world championships. Everything here runs locally in your browser.

How it works

The clock only subtracts time from the player on the move. Increment and the older delay/Fischer systems change how much time comes back, which is why the same base time can feel very different.

control "M + I"  -> M = base minutes,  I = increment seconds per move
remaining = base time - time spent thinking + (I x moves made)
Fischer increment: add I before each move begins (most common online)
estimated game length (one side) = base + (I x expected moves)
example 5+0: 5 minutes each, no increment, hard cap 10 min for both

• Base time: the starting bank of minutes for each side.
• Increment: seconds credited each move; a positive increment means a game can never be lost purely on the clock if you keep moving.
• Flag fall: hitting zero loses, but only if the opponent has mating material; otherwise it is a draw.

Worked example

Two players use a 3+2 blitz control. How long can the game run on the clock alone?

1. Base time per side: 3 minutes = 180 seconds.
2. Increment: 2 seconds added after each of that side's moves.
3. If a player makes 40 moves: they gain 40 x 2 = 80 seconds back over the game.
4. Maximum time that side could use: 180 + 80 = 260 seconds, about 4 minutes 20 seconds of thinking.

Time control reference

Common pitfalls

• Forgetting to press the clock. If you move but do not tap your side, your own clock keeps running. Pressing the clock is part of completing the move.
• Pressing before moving. Tapping the clock without completing a legal move is an illegal action in tournament play; always move first, then press.
• Confusing the two numbers. In 5+3 the 5 is minutes of base time and the 3 is seconds of increment, not 5 minutes 3 seconds.
• Assuming a flag always wins. If your opponent runs out of time but you have only a lone king (no mating material), the game is a draw, not a win.
• Underrating increment in scrambles. A small increment changes endgame technique completely; with +5 you can shuffle pieces and never flag, with +0 you can lose a won game on time.
• Picking a control that does not fit. Bullet rewards speed and pre-moves; classical rewards deep calculation. Choosing the wrong speed for your goal makes practice less useful.

Related tools

Frequently asked questions