Time Calculator
Add or subtract two durations such as 1:30:00 and 0:45:30, and see the total in several formats.
Be the first to rate this tool
The formula
Convert each time to seconds, add or subtract, then convert back: h = total / 3600, m = (total mod 3600) / 60, s = total mod 60.
Adding times that go over an hour
Minutes and seconds roll over at 60, not 100. 1:45 plus 0:30 is 2:15, not 1:75. The calculator does the carrying so you do not trip over it.
Example
A recipe step takes 1 hour 30 minutes and the next takes 45 minutes 30 seconds. Added together that is 2 hours 15 minutes 30 seconds, or 2.2583 decimal hours.
Subtracting
Pick Subtract to find the difference between two durations. If the second time is larger, you get a negative result, which tells you the first is shorter.
Examples to check
Type these into the calculator above to see how it behaves. Every result below was produced by the same calculator code that runs on this page.
| What you enter | What you get |
|---|---|
| First time (hh:mm or hh:mm:ss): 1:30:00; Add (+); Second time (hh:mm or hh:mm:ss): 0:45:30 | Result: 2:15:30 |
| First time (hh:mm or hh:mm:ss): 3:50; Add (+); Second time (hh:mm or hh:mm:ss): 2:25 | Result: 6:15:00 |
| First time (hh:mm or hh:mm:ss): 8:00; Subtract (-); Second time (hh:mm or hh:mm:ss): 0:45 | Result: 7:15:00 |
| First time (hh:mm or hh:mm:ss): 0:59:59; Add (+); Second time (hh:mm or hh:mm:ss): 0:00:01 | Result: 1:00:00 |
Time Calculator: frequently asked questions
What format do I enter the times in?
hh:mm or hh:mm:ss. Minutes and seconds must be between 00 and 59.
Can I add more than two times?
Add two, then use the answer as the first time for the next calculation.
Does it take leap years into account?
Yes. Calculations use real calendar dates, including leap days and the different lengths of months.
Is what I enter in this calculator saved or sent anywhere?
No. The calculation runs in your browser, so what you enter is not sent to our servers. We only count, anonymously, whether a tool ran successfully.
Is this calculator free to use?
Yes. It is free, needs no sign-up and has no usage limit.
Last reviewed: October 3, 2026