Exam Extra Time Calculator
Work out 10%, 25% or 50% extra time in seconds. Enter the exam duration to see the exact minutes added and the finish time — for GCSE, A-Level, IB and AP access arrangements.
Extra time is rounded up to the next whole minute. Follow your centre's JCQ guidance for access arrangements.
That's one student. ExamClock works out every student's extra-time finish and shows them live on the hall display — no manual maths.
Launch on a live display — free Show each student's extra time automaticallyAll extra-time allowances for a 1h 30m exam
| Extra time | Minutes added | New total | Finishes |
|---|---|---|---|
| Standard | — | 1h 30m | 10:30 |
| +10% | +9 min | 1h 39m | 10:39 |
| +25% | +23 min | 1h 53m | 10:53 |
| +50% | +45 min | 2h 15m | 11:15 |
How to calculate extra time for exams
Extra time for access arrangements is a percentage of the standard exam duration. To work it out: multiply the exam length by the percentage, then round up to the next whole minute so the student receives their full allowance.
Example: 25% extra time on a 1 hour 30 minute (90 minute) exam
- 90 minutes × 25% = 22.5 minutes
- Rounded up = 23 minutes of extra time
- New total = 90 + 23 = 1 hour 53 minutes
- Starting at 09:00, the exam finishes at 10:53
The most common allowance is 25% extra time, but 10% and 50% are also used depending on the student's assessed needs. Use the calculator above for any duration and percentage.
Doing this for a whole exam hall by hand?
One calculation is easy. A room full of students on different papers, each with their own extra time, is not. ExamClock handles the maths and the display for you.
Per-student extra time
Each student's +10/25/50% finish time calculated and shown automatically.
Live on any screen
Display all finish times on a TV or projector — visible from the back of the hall.
Rest breaks handled
Pause and resume individual timers — finish times adjust automatically.
Multiple papers at once
Run different exams side by side on one display, each with its own timing.
Stop calculating extra time by hand
ExamClock is $89/year for unlimited exam sessions. Try the live timer free — no account needed.
Extra Time Calculator FAQ
How do you calculate 25% extra time on an exam?
Multiply the exam duration by 0.25 and round up to the next whole minute. For a 1 hour 30 minute (90 minute) exam, 25% is 22.5 minutes, rounded up to 23 minutes — giving a total of 1 hour 53 minutes.
What is 25% extra time on a 1 hour 30 minute exam?
It adds 23 minutes, for a total of 1 hour 53 minutes. An exam starting at 09:00 would finish at 10:53.
How is exam extra time rounded?
This calculator rounds extra time up to the next whole minute so the student always receives at least their full allowance. Always follow your centre's JCQ guidance for access arrangements.
How do I show extra-time finish times to students during the exam?
ExamClock calculates each student's extra-time finish automatically and displays them live on a classroom TV or projector, alongside the main exam timer — so every candidate can see exactly when their exam ends.
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