Fischer Increment vs Bronstein Delay vs US Delay

Last reviewed: 14 August 2026. Use the current rulebook and the complete time control named by the event organiser; do not infer the required mode from the number of seconds alone.

Fischer increment adds a fixed amount of time for every move, while US delay and Bronstein delay protect a fixed number of seconds before the player’s main time is reduced. US delay and Bronstein delay display that protection differently but produce the same remaining main time when set to the same delay. The event regulations—not personal preference—determine which mode to use.

What is Fischer increment?

Fischer increment, also called cumulative increment or bonus, adds a fixed amount of time for each move. Because the full increment is added even when the player moves quickly, the player’s remaining time can rise above the amount shown at the start of the move. A control written as 10+5 normally means 10 minutes of starting time plus five seconds per move.

What is US delay?

US delay gives the player a fixed delay period before the main clock begins to count down. With a five-second delay, a move completed within five seconds does not reduce the displayed main time. If the player takes eight seconds, only three seconds are deducted from the main time. The delay does not accumulate for later moves.

What is Bronstein delay?

Bronstein delay begins counting immediately, then restores the time used up to the delay limit when the move is completed. With a five-second Bronstein delay, a three-second move restores three seconds; an eight-second move restores five seconds. The player’s main time therefore cannot increase above the amount available at the start of that move.

How do increment and delay change the clock after one move?

The table below starts with 10:00 on the player’s clock and uses a five-second increment or delay. It shows why US delay and Bronstein delay have the same practical result even though the display behaves differently.

Mode	After a 3-second move	After an 8-second move	Can main time increase?
Fischer increment, +5 seconds	10:02	9:57	Yes
US delay, 5 seconds	10:00	9:57	No
Bronstein delay, 5 seconds	10:00	9:57	No

Is Bronstein delay the same as US delay?

US delay and Bronstein delay are equivalent when the base time and delay are the same: both prevent the player’s main time from falling during the protected delay period, and neither allows unused delay to accumulate. The difference is presentation. US delay normally shows a separate countdown before main time decreases; Bronstein delay counts immediately and then restores up to the delay amount.

How should players and organisers choose the correct mode?

Read the event’s complete time control, including whether it specifies increment, bonus or delay.
Use the matching clock mode; do not substitute increment for delay or delay for increment.
Confirm whether the extra time applies from move one or from a later period.
Test the setting on every clock before the round and use the same clock type across the event where required.

FIDE’s Laws of Chess define cumulative Fischer mode and time-delay mode. US Chess also distinguishes increment notation such as inc/5 or +5 from delay notation such as d/5. Always follow the organiser’s published control and the current rulebook used for that event.

Which LEAP chess clock should you check?

Start with the required time control, then verify the exact mode and setup procedure in the current product information or manual. LEAP KK9908 and KK9909 are the priority models when buyers also need model-specific public FIDE evidence. The LEAP comparison table lists each model鈥檚 published dimensions, timing modes, memories, move counter, adjustment controls and model-specific FIDE source status.