Duration calculator
Add up hh:mm:ss durations: sum, average, total.
- Instant
- Free
- Private (processed locally)
- No sign-up
Add up hours without botching the carry
Adding “2:30 + 1:45 + 3:15” in your head is a guaranteed mistake: you forget that 60 minutes make an hour, not 100. This tool accumulates a list of durations cleanly and converts it to decimal hours, ready for payroll or invoicing.
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Paste your durations
One per line, in hh:mm:ss, hh:mm or minutes.
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Read the total
Exact sum, with no 24-hour ceiling.
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Grab the decimal
Decimal hours and average computed automatically.
Example: three work sessions
| Input | Interpretation |
|---|---|
| 2:30 | 2 h 30 min |
| 1:45 | 1 h 45 min |
| 3:15 | 3 h 15 min |
| Total | 7:30:00 = 7.5 h · average 2:30:00 |
Payroll tip: the total in decimal hours (here 7.5 h) multiplies directly by your hourly rate. Never confuse 7:30 (seven hours thirty) with 7.30 — it is 7.5.
Frequently asked questions
How do I enter durations?
One duration per line. Three parts “1:30:00” = 1 h 30 min 00 s. Two parts “2:15” = 2 h 15 min. A bare number “90” = 90 minutes. You can mix formats in the same list.
Why convert to decimal hours?
Because payroll and billing use decimal hours: 7 h 30 min is 7.5 h. Multiplying 7.5 by an hourly rate is instant, whereas multiplying “7:30” is not. The conversion avoids the classic “7.30” mistake.
Can the total exceed 24 hours?
Yes: the sum accumulates without wrapping to zero. 20 trips of 1 h 15 give 25:00:00, shown as is — it is not a time of day but a total duration.
What is the average for?
To find the typical duration of a series: average time per task on a timesheet, average episode length for an editor, average pace across several sessions. It updates with every line added.