The Chess Timer

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Increment vs Delay: Fischer, Bronstein and Simple Delay

Published September 28, 2026 · 9 min read

Increment vs delay in chess comes down to one question: can your clock ever show more time than it did at the start of your move? With a Fischer increment it can, because a fixed number of seconds is added after every move. With a delay, whether simple (US) delay or Bronstein delay, it cannot: the clock only protects the first few seconds of each move. Below you can watch both run on the same moves, then read how each mode works and who uses it.

What is the difference between increment and delay in chess?

Both add time for each move on top of the base time, so a long endgame of quick moves is not lost on the clock alone. FIDE’s Laws of Chess say a time control includes “any additional amount of time added with each move” (Article 6.3.1) and name two ways to add it: the cumulative (Fischer) mode, “where a player receives an extra amount of time (often 30 seconds) prior to each move”, and the delay (Bronstein) mode, where the countdown of the main thinking time “only commences after the fixed extra time has expired” (6.3.2 and the glossary).

US Chess splits the second idea by display: “There are two forms of delay, ‘simple’ (or ‘US’) delay and ‘Bronstein’ delay. Both are mathematically equivalent, equally acceptable for use under the rules, and just differ in how the delay is displayed on the clock screen” (Rule 5B1, TD tip). Three names, two behaviors.

Fischer increment: time is added after every move

With an increment of n seconds, n seconds are added to your clock every time you complete a move. Move in less than n seconds and your time goes up. US Chess describes it as: “With increment, (also commonly known as ‘Fischer’ and ‘bonus’), the increment time is added to the main time each turn, regardless of the amount of time it took the player to move” (Rule 5B1, TD tip).

The Chess Timer’s Fischer setting reads “Adds n s to your clock after every move you make”, and the increment for move one is on the clock from the start: a 3+2 game begins at 3:02, as tournament clocks do. The guide explains why the rulebooks want it that way.

Bronstein delay: you get back what you used, up to the limit

With a Bronstein delay of n seconds, your main time counts down from the moment your clock starts. When you press, the clock gives back the time you used on that move, but never more than n seconds. With n = 2, think for 1 second and you get 1 back; think for 6 and you get 2 back. Your clock can return to where it started the move, never above it.

In US Chess’s words, Bronstein delay “combines the delay time and the main time into a single display. If a player uses the entire delay time or more for a move, the clock will add the delay time to the main time. If a player uses less than the delay time for a move, the clock will go back to the time it had at the beginning of the move” (Rule 5B1, TD tip). The Chess Timer’s Bronstein setting reads “After each move you get back the time you used, up to n s”.

Simple (US) delay: the clock waits before it counts down

With a simple delay of n seconds, your main time stands still for the first n seconds of your turn. On The Chess Timer a small Delay countdown under your time shows those seconds ticking away; when it reaches zero the main time starts to fall. Move within the delay and your time is untouched. FIDE’s Article 6.3.2 describes exactly this: “Provided the player presses his/her clock before the expiration of the fixed extra time, the main thinking time does not change, irrespective of the proportion of the fixed extra time used.”

US Chess notes that simple delay “separates the delay time from the main time” on the display (Rule 5B1, TD tip) and writes it d/5, as in G/30 d/5: game in 30 minutes with a 5-second delay (Rule 5B2).

Watch increment and delay side by side

The two small clocks below both have a base time of 1:00 and play the same five moves, taking 1, 4, 2, 6 and 1 seconds. The left clock uses a Fischer increment of 2 seconds, the right one a simple delay of 2 seconds. Before the first move the Fischer clock already shows 1:02, because the increment for move one is added up front; the delay clock shows 1:00.

Fischer +2 s1:02
Delay 2 s1:00
Start

The arithmetic behind it: “used” is the time spent on the move, “shows” the time displayed after it.

Move Used Fischer +2 s: calculation Fischer shows Simple delay 2 s: calculation Delay shows
start – 1:00 + 2 s for move one 1:02 no increment; the delay only runs during a move 1:00
1 1 s 1:02 − 1 s + 2 s 1:03 1 s inside the delay, main time untouched 1:00
2 4 s 1:03 − 4 s + 2 s 1:01 first 2 s free, then 2 s off the main time 0:58
3 2 s 1:01 − 2 s + 2 s 1:01 2 s inside the delay, main time untouched 0:58
4 6 s 1:01 − 6 s + 2 s 0:57 first 2 s free, then 4 s off the main time 0:54
5 1 s 0:57 − 1 s + 2 s 0:58 1 s inside the delay, main time untouched 0:54

After five moves and 14 seconds of thinking, the Fischer clock is 2 seconds below its 1:00 base time (4 below the 1:02 it showed at the start) and the delay clock 6 seconds below. The Fischer clock also went up twice (moves 1 and 5, each faster than the increment); the delay clock never did.

A third clock with a Bronstein delay of 2 seconds would end the same moves at 1:00, 0:58, 0:58, 0:54, 0:54, identical to the simple-delay column. Only the picture during the move differs: on move 1 the Bronstein clock dips to 0:59 and jumps back to 1:00 at the press, while the simple-delay clock never leaves 1:00.

Why Bronstein and simple delay end each move with the same time

Both modes protect the same n seconds of every move; they just protect them at different moments.

  • Simple delay protects them first: the main time stands still for n seconds, then counts down. Time lost on the move = max(0, used − n).
  • Bronstein protects them afterwards: the main time counts down for the whole move and min(used, n) is refunded at the press. Time lost = used − min(used, n) = max(0, used − n).

Same formula, same result after every move. That is why US Chess calls the two “mathematically equivalent” (Rule 5B1, TD tip) and accepts a Bronstein-capable clock for a delay time control (Rule 5F2a), why FIDE needs only one definition for “delay (Bronstein) mode”, and why our home page FAQ says both kinds of delay leave the same time on the clock after each move.

What neither delay can do is what Fischer does: build a reserve. Under increment a run of fast moves earns time you can spend later; under either delay, fast moves merely cost nothing.

When is increment used, and when delay?

FIDE’s own events use increment. The Laws define rapid and blitz by “the allotted time plus 60 times any increment” (Appendices A.1 and B.1), and FIDE’s championships are increment controls: the World Rapid Championship is played at “15 minutes + 10 seconds increment per move, starting from move 1” and the World Blitz Championship at “3 minutes + 2 seconds increment per move, starting from move 1” (2025 regulations, Articles 4.2.2.1 and 4.3.1.2.1). The Chess Olympiad 2026 uses 90 minutes for 40 moves, then 30 minutes for the rest of the game, “with an increment of 30 seconds per move starting from move 1” (Regulations, Article 4.3.5). The Laws define delay mode too, but the event regulations above all specify increment.

US Chess makes delay the default. Its rulebook says “Standard delay is 5 seconds (regular or dual); and 3 seconds (quick)”, while “when used, standard increment is 30 seconds (Regular)” (Rule 5C, TD TIP). If an organizer forgets to specify either, “the minimum recommended delay specified in rule 5E shall apply” (Rule 5E2), and a “delay capable clock is the standard timer for use with a delay time control” (Rule 5F2). Of the nineteen example time controls in the TD TIP under Rule 5C, twelve use a delay, five an increment and two neither. US Chess blitz is the exception the other way: games “typically are set at five minutes and do not use time delay”, and the standard control is “G/5 with no delay” (Chapter 11).

Both federations agree that the increment or delay runs from move one (FIDE glossary “increment”; US Chess Rules 5E1 and 16B2) and that the full control, including the increment or delay, is announced in advance (FIDE 6.3.1; US Chess 5B2). For the other differences between the rule sets, see FIDE vs US Chess (USCF) clock rules compared; for how the increment moves the blitz, rapid and classical boundaries, see Chess time controls explained.

Which should you choose for a casual game?

  • You want the game to end on time: a delay of 2–5 seconds. Nobody can hoard time.
  • You hate losing won endgames on the clock: an increment of 2–10 seconds. Obvious moves pay for themselves.
  • Practising for a US Chess event: its delay, typically d/5 for slow games and d/3 for quick chess (Rule 5C, TD TIP).
  • Practising for a FIDE-rated event: increment, +30 classical, +10 rapid, +2 blitz, as in FIDE’s own championships.

Try it

  • G/30 d/5: the US delay preset, 30 minutes with a 5-second simple delay.
  • 3+2: 3 minutes with a 2-second Fischer increment, the FIDE World Blitz control.

To try Bronstein, tap Custom and choose Bronstein under Added time per move. Starting and pressing the clock is covered in How does a chess clock work?.

Sources

Checked on 2026-09-28: