Short answer: bonus time adds a fixed number of extra seconds to your clock after every move you make. It exists so a player is not flagged, meaning they lose on time, in a position they were clearly winning. Most people call it "bonus time" or "the extra seconds", but the proper name is increment. Here is exactly how it works, why it exists, and the one type of bonus time that behaves a little differently.
The Quick Answer
Every game with bonus time has two numbers, usually written like 5+3. The first is your starting time in minutes. The second is the bonus in seconds you get back after each move.
Reading "5+3"
So you begin with 5 minutes, and every single time you complete a move, 3 seconds drop back onto your clock. Move quickly and you can end up with more time than you started with. Move too slowly and you still run out.
How the Bonus Actually Adds Up
Here is the part that surprises people the first time they see it. Because the bonus lands after every move, it stacks up over a whole game. If you play a 40 move game at 5+3, that is 40 lots of 3 seconds, which is 2 extra minutes banked across the game on top of your starting 5.
That changes how the endgame feels. Without bonus time, a player nursing 10 seconds against a big material lead can just shuffle pieces and hope the other player flags. With bonus time, those 3 seconds a move keep the clock alive, so games are decided on the board far more often.
The add-time-per-move system is often called Fischer increment, after world champion Bobby Fischer, who patented a digital clock that did exactly this back in 1988. The goal was simple: reward players for moving efficiently and stop good games ending in a silly time scramble.
The Two Kinds of Bonus Time
Not all bonus time behaves the same way. There are two systems, and the difference is whether the unused seconds carry over.
Increment (Fischer)
The bonus is added to your clock and it accumulates. If your bonus is 3 seconds and you only spend 1 second on a move, you keep the 2 second difference. This is the common one, both online and at most modern over-the-board events. It is what "5+3" means.
Delay (Bronstein or US delay)
Your clock waits for a few seconds before it starts counting down. If you move within that window you lose no time, but any unused delay does not bank, it simply resets each move. Delay protects every single move but never lets your total time climb. It is often written like 5 d3 (5 minutes, 3 second delay).
| Increment (Fischer) | Delay (Bronstein) | |
|---|---|---|
| When you get it | Added after your move | Before your clock starts ticking |
| Unused time | Banked, carries over | Lost, resets each move |
| Can your clock go up? | Yes, if you move fast | No, it only pauses |
| Written as | 5+3, 5 | 3 | 5 d3 |
| Where you see it | Online, most modern events | US over-the-board, some clubs |
Why Bonus Time Exists
It comes down to fairness. Before increment and delay, a player could be completely lost on the board but still win by making instant moves until the other player's flag fell. Bonus time fixes three things at once:
- It rewards good moves, not fast hands. You are less likely to lose a won game just because you thought carefully.
- It keeps endgames playable. Those few seconds a move give you room to actually checkmate or promote a pawn.
- It makes results cleaner for organizers. Fewer games are decided by a pure time scramble, which means fewer disputes.
The trade-off is that bonus time makes games run a little longer, which matters if you are the one planning the schedule. For the full picture on how base time and increment combine into blitz, rapid and classical, read our complete guide to chess time controls, and if the notation itself trips you up, our guide to reading chess clock notation decodes it.
Bonus Time and Winning on the Clock
One common myth: people assume bonus time means you can never lose on time. Not true. Bonus time only buys you the bonus. If your increment is 3 seconds but you keep spending 10 seconds a move, your clock still drifts down to zero, and when it hits zero you lose, winning position or not.
What bonus time really does is give you a floor. As long as you can find your moves inside the bonus window, you can keep playing forever. Spend more than the bonus and you are still slowly burning your reserve.
Example: A Club Night at 10+5
Want to feel it in action? Our free online chess clock lets you set any bonus time and watch the seconds add back after each move, right in your browser, no signup.
Your bonus time affects how long each round takes and therefore how many rounds fit your night. ChessHost, our free chess tournament organizer, sets up rounds and generates pairings in seconds, so once you have picked a clock you can run the whole event smoothly.
Frequently Asked Questions
How does bonus time work in chess?
Bonus time, usually called increment, adds a fixed number of seconds to your clock every time you complete a move. In a 5+3 game you start with 5 minutes and gain 3 seconds after each move. If you move faster than the bonus, your remaining time can actually go up.
Is bonus time the same as increment?
Yes. Bonus time is the casual name for what is officially called increment, or Fischer increment after Bobby Fischer who patented the idea. Both describe the extra seconds added to your clock after every move you make.
Does bonus time carry over between moves?
With increment, yes. Any bonus seconds you do not use stay on your clock and build up over the game, so a fast player can bank several minutes. With a simple delay, unused bonus time does not carry over, it just resets each move.
What is the difference between increment and delay?
With increment (Fischer), the bonus seconds are added to your clock and accumulate. With delay (Bronstein or US delay), your clock pauses for a few seconds before it starts counting down, but any unused delay is not banked. Increment rewards fast play, delay simply protects each move.
Can you still lose on time with bonus time?
Yes. Bonus time reduces the chance of being flagged but does not remove it. If you keep spending more than the bonus each move, your clock still runs down to zero and you lose, even in a winning position. The bonus only buys you a few seconds per move.
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