Chess delay vs increment: what is the difference?
The short answer to chess delay vs increment is this: with increment you can finish a move with more time on your clock than you started it with, while delay can only ever protect the time you already have. Unused increment is banked. Unused delay evaporates the moment you press.
Everything else follows from that one asymmetry. A 5-second increment game can drift longer as both players rattle out forced sequences and pocket the seconds; a 5-second delay game cannot, because nothing carries forward. Below is how the three common systems work, what a single move actually costs under each, and which federations use which.
Chess delay vs increment: the rule in one line each
There are three systems in wide use, and they differ only in when the extra seconds are applied.
- Fischer increment. A fixed amount is added to your clock every time you press it. Move in two seconds with a 5-second increment and you are three seconds richer than before. The bonus accumulates without limit.
- Simple delay (also called US delay). When your turn starts, a separate countdown runs first. Your main clock does not move at all during it. Press within the delay and you spend nothing. Only after the delay expires does your main time start falling.
- Bronstein delay. The delay is added to your clock at the start of your move, and whatever you did not use is taken off again when you press. Spend three seconds of a 5-second Bronstein delay and you keep three, not five.
FIDE’s Laws of Chess describe delay mode this way: both players receive an allotted main thinking time plus a fixed extra time with every move, and the countdown of the main thinking time only commences after the fixed extra time has expired. The Laws treat “delay” and “Bronstein” as one mode. Cumulative, or Fischer, mode is named separately, as an amount added to a player’s clock after each move.
The three systems side by side
| Fischer increment | Simple (US) delay | Bronstein delay | |
|---|---|---|---|
| Can your total time go up? | Yes | No | No |
| When the bonus applies | On pressing the clock | Before your main time starts | Added first, unused part removed on pressing |
| Unused bonus | Kept | Lost | Lost |
| Display during the move | Main time counting down | A separate delay countdown, then main time | Main time already topped up by the delay, counting down |
| Clock after a fast move | More than you started with | Unchanged | Unchanged |
| Common setting | 2, 3, 5, 10 or 30 seconds | 3 or 5 seconds | 3 or 5 seconds |
| Usually written as | 5|5, 15|10, 90+30 | G/90;d5 | G/90;d5, clock in Bronstein mode |
A worked example: what a 10-second think costs
Start each side with 10:00 on the clock and a 5-second bonus. You think for ten seconds, then press.
- Fischer increment. Ten seconds come off, so the clock reads 9:50, then five are added back. You finish on 9:55.
- Simple delay. The first five seconds are covered by the delay countdown and cost you nothing. The remaining five come off your main clock. You finish on 9:55.
- Bronstein delay. Five seconds go on before you start, putting you on 10:05. Ten seconds come off, and because you used the whole delay there is nothing to remove when you press. You finish on 9:55.
Now repeat it with a three-second think. Fischer leaves you on 10:02, because you spent three and received five. Simple delay leaves you on 10:00, because the grace period covered the whole move. Bronstein puts you on 10:05, takes three off to 10:02, then removes the two you did not use, so you are back on 10:00. That is the whole difference in miniature: only the increment player gained anything.
The practical consequence. Seconds saved under increment are still yours ten moves later, so a fast mover builds a cushion out of nothing. Under delay your main time only ever shrinks. The absolute ceiling is the same shape either way — (base + bonus × moves) × 2 for the pair of you — but the bonus is small under delay and unbounded in practice under increment. Over 60 moves a side, G/90;d5 tops out at (90 min + 300 s) × 2, or 3 hours 10 minutes; 90+30 tops out at (90 + 30 min) × 2, or 4 hours.
Simple delay and Bronstein leave you with identical time
After any given move, simple delay and Bronstein delay produce exactly the same reading. Both give a grace period of the same length, and both refuse to bank what you did not use. The two differ only in what the display does while you are thinking.
Simple delay keeps the two quantities apart. You see a small countdown, or a flashing indicator, ticking off the grace seconds while your main time sits still. Bronstein merges them, so the number on screen is the whole of what you have for this move. The advantage of Bronstein is that the figure showing is your true remaining time for the move, with nothing to add mentally. The advantage of simple delay is that you can watch the grace period drain and know precisely when your real time starts burning. Pick on preference, not on mathematics. Our Bronstein delay chess clock runs both modes from the same starting time, so you can watch the two displays behave differently while the totals stay in step.
Where each one is used
The split is broadly geographic. FIDE events lean on increment. The classical pattern across most FIDE events is 90 minutes for the first 40 moves plus 30 minutes for the rest of the game, with a 30-second increment from move one; the 2024 World Championship ran a longer version of the same idea, 120 minutes for 40 moves then 30 minutes, with the 30-second increment starting at move 41. Increment is also baked into how the Laws classify a game: rapid and blitz are defined by the allotted time plus 60 times any increment — blitz at 10 minutes or less by that sum, rapid above 10 and under 60.
US Chess events lean on delay, and simple delay is the form of delay most used in the United States. Five seconds is the usual figure for sudden-death controls, written G/90;d5, and a great many club and scholastic events are still run that way. Bronstein mode reaches the same numbers, so a clock offering only Bronstein costs you nothing. Where an increment control is scheduled and no increment-capable clock is on hand, organisers commonly substitute a delay of the same length; confirm it with the arbiter, since the announced control governs.
Online play never uses delay. The major sites offer increment or nothing at all, which is why formats such as 3|2 and 15|10 read as normal while a “d5” suffix does not; plenty of the most-played online pools, 3|0 and 10|0 among them, have no bonus whatsoever. If the notation itself is unfamiliar, chess time controls explained walks through how each format is written and what it means at the board.
Which should you set?
Set an increment if you want games that end in a played-out position rather than a flag fall, and if you do not mind a session running past its scheduled slot. Thirty seconds a move gives most players room to play out a won endgame instead of racing. Two or three seconds is enough to keep a blitz game from turning into a contest of hand speed.
Choose delay if you are practising for a US Chess event, if you are running a schedule where round lengths have to be predictable, or if you simply want a clock that never hands anything back. Five seconds per move is the standard figure. For deeper reading on either side, see what increment is in chess and what Bronstein delay is.
Try both before your next game
The fastest way to feel the difference between chess delay vs increment is to play a few moves under each. The chess clock on this site runs Fischer increment, simple delay and Bronstein delay in the browser, free and unlimited with nothing to install, so you can set 5|5 and G/5;d5 back to back and watch what happens to your total after a quick move. It also plays multi-stage tournament controls rather than merely storing them.
For over-the-board use away from a laptop, the Chess Timer app on the App Store and Google Play gives you a two-zone clock with Fischer increment, eleven presets, sixteen themes and full offline operation. It is free to download, with a premium unlock after three start and pause actions. Delay, Bronstein and multi-stage playback are web-clock features rather than app features, so keep this page bookmarked if delay is what your event uses.