Chess clock with increment

What increment actually does

Fischer increment adds a fixed number of seconds to your own clock every time you complete a move and press. Because the seconds are added rather than merely protected, a player who moves quickly ends up with more time than they started with. That is the property that separates increment from every kind of delay.

Take a 3|2 game. If both players average one second a move, each of them is gaining a second a move, and after forty moves they are both better off than at move one. Take the same game at 5|0 and the clock only ever goes down.

Why it changed how chess is played

Before increment, a won endgame could be lost purely because there was no time left to play it — the notorious scramble where both players shuffled pieces and the flag decided the result. Bobby Fischer's proposal was to hand a small amount of time back on every move so that a player always has enough to make a legal move and press.

The effect on modern chess is easy to see. A thirty-second increment means a technically won rook endgame can be converted properly rather than blitzed out, and FIDE's standard classical control now carries an increment from move one for exactly that reason.

Choosing an increment

One thing hardware clocks disagree on

Some digital clocks credit the increment at the start of the first move, so a 5+3 game shows 5:03 before anyone has touched a piece. Others credit it only when you press, so the display starts at 5:00. The difference is a single increment across the whole game and it never decides anything, but it does explain why two clocks in the same room can show different numbers on move one.

This clock credits the increment on the press, matching the app. Neither convention is wrong.