Increment is the mechanism that stops a time scramble turning a won game into a lottery. Without it, any position can be lost on the flag regardless of how good it is. With it, a player who plays accurately can always find enough time to finish the job. Here is a precise explanation of how each timing method works, how they feel at the board, and why tournaments choose one over another.
Why increment exists
In a game with no increment — a pure countdown — a player who has outplayed their opponent can still lose if they run their clock low. The winning side has to move fast enough not to flag. That creates a second, separate game running alongside the chess: a speed contest that has nothing to do with who played better. For casual blitz that tension is part of the fun. For serious chess it is a flaw.
Increment was introduced to give a player who is moving accurately enough time to keep moving accurately. It does not eliminate time pressure entirely — that would make the clock pointless — but it removes the absurdity of flagging in a position where checkmate is one move away.
Fischer increment
Fischer increment — named after Bobby Fischer, who proposed and patented the idea — adds a fixed number of seconds to your clock after every move you make. The addition happens when you press the clock button. You receive the full increment regardless of how long you thought.
The format is written as base + increment: 5+3 means five minutes on the clock at the start, plus three seconds added each time you press. If you spend one second on your move, you net two seconds. If you spend four seconds, you net nothing. Spend less than the increment on every move and your clock actually grows.
This has a significant effect on endgames. A player with ten seconds left but a three-second increment can still play a technically demanding endgame if they move quickly and accurately. Without increment, ten seconds is ten moves at best. The same player with increment can potentially play indefinitely — the clock replenishes faster than it drains.
Tournament blitz almost universally uses Fischer increment. The standard FIDE World Blitz Championship format is 3+2. The standard improvement-focused rapid control is 15+10. Increment is why those games produce real chess in the endgame rather than desperate flagging.
Bronstein delay
Bronstein delay — named after David Bronstein, who developed the idea independently around the same time as Fischer — works differently. Instead of adding time after your move, it delays the start of your clock countdown at the beginning of each move.
When it is your turn, the clock pauses for the delay period before it starts counting down. If you move within the delay window, your overall time is completely unchanged — you did not spend any of your main time at all. If you take longer than the delay, only the excess counts against you.
The format is written with d for delay: G/5 d3 means five minutes with a three-second delay per move. If you always move within three seconds, you will still have exactly five minutes when the game ends. If you occasionally think for thirty seconds, you spend twenty-seven of those against your clock.
The practical feel is different from increment. With Bronstein delay, time can never increase — it can only stay the same or decrease. You cannot bank time by moving quickly. The delay simply absorbs instantaneous moves and brief thoughts; the clock only runs when you are genuinely thinking.
Simple delay (also called US delay)
Simple delay works almost identically to Bronstein delay from the player’s perspective: a countdown buffer before the main clock starts ticking each move. The difference is technical — in Bronstein delay the buffer is always exactly the delay value; in simple delay the displayed time behaves slightly differently when time is running low. In practice most players cannot tell the difference during a game.
Simple delay is the standard in US Chess (USCF) events. Many American tournament clocks default to this method. If you are playing in USCF-rated events, simple delay is what you will encounter.
Hourglass timing
A less common variant worth knowing: hourglass (or Fisher delay reversed) gives the time you spend on your move directly to your opponent. If you think for thirty seconds, your clock drops by thirty and your opponent’s clock rises by thirty. It creates strange dynamics — playing slowly helps your opponent — and is occasionally used in themed events or casual play. No major federation uses it for standard rated games.
Which method does each federation use?
FIDE (the international governing body) uses Fischer increment for all its official events — World Championships, Olympiad, Grand Prix, World Blitz and Rapid Championships. The increment is built into the time control notation: 90+30 means ninety minutes for the game plus thirty seconds increment from move one.
US Chess (USCF) has traditionally used simple delay, partly for historical reasons and partly because many established US tournament clocks were built around delay rather than increment. There has been gradual drift toward increment at higher levels, but delay remains common at club and state level.
ECF (England) and most European federations follow FIDE formats, so increment is standard.
Increment in the notation
Standard time control notation puts the increment after a plus sign: 90+30, 15+10, 3+2. If there is no plus sign, the control has no increment: 5+0 is five minutes sudden death. When delay is used, it is written with a d: G/30 d5.
Online platforms sometimes display this differently. Lichess shows controls as “5+3” and labels them by category. Chess.com uses similar notation. The format is consistent enough that once you know to read the number after the + as seconds of increment per move, the shorthand becomes clear.
Choosing the right control
For casual home play with no increment, pure countdown is fine — the flag pressure is part of the game. For practice aimed at improvement, Fischer increment is better because it keeps endgames honest.
If you want to feel the difference before committing to a time control, the online clock supports both increment and delay across all formats. Try 5+0 versus 5+3 back to back and the difference in how the endgame phase feels is immediately obvious. For the delay side, 5 d2 and 15 d5 are direct comparisons to their increment equivalents. The blitz and rapid pages list all increment and delay controls with notes on where each is used.
For a deeper look at how these controls are used in physical clocks, the how to set up a chess clock guide covers the practical side of configuring increment and delay on digital hardware.