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Time

Time Calculator

Add or subtract durations in hours, minutes, and seconds. Keep a running total across tasks, clips, or time adjustments.

Add and subtract durations

These are amounts of time, not times on a clock. Hours continue past 24.

Duration 1
Duration 2

2 of 20 durations

Use 1–20 rows. Each row needs at least one number; blank components mean 0. Hours: 0–999,999,999. Minutes and seconds: 0–59. Use whole digits without commas or signs, and choose Subtract for a negative contribution.

Example: two task durations minus a ten-minute break.

Total duration · hours:minutes:seconds

Enter your durations, then select Calculate.

Calculations run in your browser. Press Enter in a duration field to calculate. Successful totals appear in this tab's Recent calculations.

Worked time calculations

Tasks and a break

1:45:30 + 0:35:45 − 0:10:00

2:11:15

The two durations add to 2:21:15. Removing ten minutes leaves 7,875 seconds, or exactly 2.1875 hours.

Carry into the next hour

0:59:59 + 0:00:01

1:00:00

Sixty seconds make a minute and sixty minutes make an hour. Enter 90 minutes as 1 hour and 30 minutes; each minute and second input is limited to 0–59.

A signed difference

1:00:00 − 2:30:00

−1:30:00

The minus sign applies to the complete duration: negative 90 minutes, or −1.5 hours. It does not mean “minus one hour, plus thirty minutes.”

How the calculation works

Each row becomes 3,600 × hours + 60 × minutes + seconds. Add rows contribute a positive amount; Subtract rows contribute a negative amount. The signed seconds are summed exactly and then split into hours, minutes, and seconds for display.

One minute is exactly 60 seconds and one hour is exactly 3,600 seconds, as listed in NIST's unit conversion tables. The result is an elapsed amount of time, so 26 hours remains 26:00:00 and does not wrap to 2:00.

Decimal hours divide the total seconds by 3,600; decimal minutes divide by 60. They show 4 decimal places by default, with 0, 2, 4, 6, or 10 available. Exact halfway values round away from zero; ≈ identifies display rounding. Changing decimal precision does not change the exact duration or add a recent-history record.

Use 1–20 rows. Hours accept up to 9 digits and minutes/seconds up to 2 digits, including leading zeros. Each input is limited to 32 characters including surrounding whitespace. Empty components mean zero, but a completely empty row needs a number or must be removed. Enter 0 explicitly for a zero duration. Negative signs, commas, fractions, and decimal or exponent inputs are not accepted.

This tool adds and subtracts elapsed durations. It does not resolve dates, time zones, daylight-saving changes, leap seconds, or pay rules. For a difference between clock times, use the linked Time Duration Calculator; for calendar dates, use the Date Difference Calculator.

Common questions

Why is 1 hour 30 minutes equal to 1.5 hours?

Thirty minutes is 30 ÷ 60 = 0.5 hours. Time components use base 60 for minutes and seconds, while decimal hours use ordinary decimal fractions. 1.30 decimal hours would mean 1 hour and 18 minutes.

Can the total be negative or longer than one day?

Yes. A subtraction larger than the time added produces a negative total. Hours keep increasing beyond 24, so durations covering several days remain exact.

Will the order of the rows affect the total?

With the same Add/Subtract signs, rearranging rows keeps the final total unchanged. The running subtotals can change because they describe a different order.

Can I leave unused hours or seconds blank?

Yes, a blank component counts as zero. Every row must still contain at least one number. Remove unused rows or enter an explicit zero if you want them included.