A time control sets how long each player has to think. Notations like 90+30 and 40/120 look like simple arithmetic, but each number means something different depending on where it sits. Different organizers also write the same control in different orders, so it pays to know what each piece does before your clock starts.
The parts
A time control notation can combine four pieces:
- Minutes: the starting time, or the time allowed for a block of moves.
- Moves: the number of moves that block covers, written before a slash, as in
40/120. +(increment): seconds added to the clock before each move.d(delay): a fixed window at the start of each move during which the clock pauses.
SD (sudden death) marks the final stage after the timed move blocks. G (game) means one allowance for the whole game, as in G/90. The FIDE glossary defines neither abbreviation, and clubs and federations use them informally.
Reading 90+30
90+30 gives each player 90 minutes for the whole game, plus 30 seconds added before each move. The FIDE glossary defines an increment as "an amount of time (from 2 to 60 seconds) added from the start before each move for the player." The FIDE glossary's own example of a time control is "40 moves in 90 minutes, all the moves in 30 minutes, plus 30 seconds cumulatively from move 1."
Take a game of 40 moves where you average 2 minutes 45 seconds per move. You spend 110 minutes. Your budget is 90 minutes plus 40 increments of 30 seconds, which is 20 minutes, so 110 minutes in total. You finish with nothing left. If you average 2 minutes 30 seconds instead, you spend 100 minutes against the same 110-minute budget and finish with 10 minutes.
Reading 40/120 and 40/90
40/120 is a two-stage control. In this moves-first format, the number before the slash is the move target and the number after it is the time allowed: each player gets 120 minutes for the first 40 moves. Once players reach move 40, the clock adds time for the rest of the game. That second stage is often written SD60, meaning 60 minutes for all remaining moves.
40/90 works the same way, providing 90 minutes for the first 40 moves.
Reading d5
d5 is a 5-second delay. On each move, the clock waits 5 seconds before counting down your main time. Move within 5 seconds, and you use no clock time at all. Because delay is a fixed window, unused delay is lost and does not carry to the next move.
An increment works differently. Say you have a 5-second increment and you move in 2 seconds. The 5 seconds are added before your move, you use 2, and you finish the move with 3 seconds more than you started with. Increment accumulates across the game. Delay never does.
The FIDE Laws describe delay as "time-delay mode," in which each player receives a "fixed extra time" with every move, and the main thinking time starts only after that fixed extra time has run out. This guide and the ScanChess calculator write it as d5.
Why the same control looks different
The confusion comes from the fact that the same control can be written as 40/120 or as 120/40, and a clock or software may expect a different order again. Because notation is not standardized, always verify what the number before the slash stands for in that specific event's rules.
The ScanChess time control calculator takes the minutes-first form, such as 15+10, and accepts d5 for delay. Enter the control in the form the tool expects.
Before a tournament
- Confirm whether the event uses delay or increment. They are not interchangeable, and treating delay like increment can cost you a game on time.
- Verify whether the increment applies from move 1 or only after the first time control. If the announcement format is ambiguous, write the numbers down and clarify them with the arbiter before round 1.
