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Time Calculator

Add and subtract hours, minutes and seconds.

Inputs

Add / subtract times
= 5,400 seconds
= 2,730 seconds

Results

Total time
2:15:30
Decimal hours
2.2583
Decimal minutes
135.5
Total seconds
8,130

What is the Time Calculator?

A time calculator is a free online tool that adds and subtracts hours, minutes and seconds — perfect for totaling timesheets, run splits, video durations or any time-based arithmetic.

Time Calculator formula

Times are normalized to a single unit (seconds), summed or subtracted, then converted back to h:mm:ss form. 1 hour = 60 minutes = 3,600 seconds; the calculator carries minutes into hours and seconds into minutes automatically when a value exceeds 60.

How to use the Time calculator

  1. 1Pick the operation: Add or Subtract.
  2. 2Enter the first time as h:mm:ss (e.g. 02:30:15).
  3. 3Enter the second time the same way.
  4. 4Click Calculate to see the total in h:mm:ss form plus a decimal-hours equivalent.
  5. 5Chain multiple times by reusing the result as the new first input.

Example calculation

Adding 02:45:30 + 01:20:45 = 04:06:15 (4 hours, 6 minutes, 15 seconds), which equals 4.1042 decimal hours. Subtracting 01:30:00 from 03:15:00 gives 01:45:00.

Frequently asked questions

How do I add hours and minutes?
Convert both values to minutes, add them, then convert back: divide total minutes by 60 for hours and use the remainder for minutes. This calculator does that automatically with h:mm:ss inputs.
What is decimal time?
Decimal time expresses the minutes portion of a duration as a fraction of an hour. 30 minutes = 0.5 hours, 15 minutes = 0.25 hours, so 2:30 becomes 2.5 decimal hours — useful for payroll and billing.
How many seconds are in an hour?
One hour = 60 minutes × 60 seconds = 3,600 seconds. To convert hours to seconds, multiply by 3,600; to convert seconds to hours, divide by 3,600.
Can I subtract a larger time from a smaller one?
Yes. The calculator will return the absolute difference in h:mm:ss form. If you need signed results (negative time), subtract smaller-from-larger manually first.
How do I total a timesheet with multiple entries?
Add the first two times, then use the result as the first input and add the next time. Repeat for each entry. For paid hours, convert the final h:mm:ss to decimal hours and multiply by your hourly rate.

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