Net activity time
01:20:00 plus 00:45:30 minus 00:15:00 equals 01:50:30, or approximately 1.841667 decimal hours.
Add or subtract elapsed durations
Use HH:MM:SS, MM:SS, 90s, 2.5m, or 1h. Prefix a line with − (type the minus key) to subtract it. These are durations, not clock-in and clock-out times.
Duration total
Net total × 1
01:50:30.000
Decimal hours1.841667
Total minutes110.500
Total seconds6630
Before multiplication: 01:50:30.000. A negative result means subtracted time exceeds added time.
Check the arithmetic
| Line | Duration | Running total |
|---|---|---|
| 1 | 01:20:00 | 01:20:00.000 |
| 2 | 00:45:30 | 02:05:30.000 |
| 3 | -00:15:00 | 01:50:30.000 |
Inputs and results are processed in this browser. This tool does not upload your entries or retain them after a page refresh.
How to use the Time Duration Calculator
- 01
Enter one elapsed duration per line using HH:MM:SS, MM:SS, or a unit suffix.
- 02
Prefix a duration with a minus sign to deduct it. Leave other lines positive.
- 03
Optionally multiply the net duration, then copy or download the result.
Examples
Repeat a routine
A 12-minute block plus an 8-minute block totals 20 minutes. A multiplier of 3 produces one hour; the table continues to show the original unmultiplied running totals.
Duration is different from wall-clock time
02:30 means two minutes and thirty seconds in the two-part MM:SS format. Use 02:30:00 for two hours and thirty minutes. A duration has no date, time zone, midnight rollover, or daylight saving adjustment.
Conversion and arithmetic
The calculator turns each entry into milliseconds, applies its sign, adds the entries, and multiplies the net total once. Decimal hours equal total seconds divided by 3,600; total minutes equal total seconds divided by 60.
Precision and negative totals
Fractional seconds accept up to three decimal places. Unit-suffix values such as 1.5h are also accepted. A negative total is retained rather than clamped to zero, so deductions can be checked explicitly.
What to know
- Up to 500 duration lines and a multiplier up to 1,000.
- Individual durations and the absolute final total are capped at 36,500 days.
Common questions
Can I paste clock-in and clock-out pairs?
No. Enter elapsed durations here. Use the work hours calculator to calculate time between shifts and subtract breaks.
Do hours wrap after 24?
No. Thirty hours displays as 30:00:00 because this is elapsed time.
What happens to blank lines?
Blank lines are ignored. An entirely blank input produces an instruction instead of a meaningful zero total.