Time Calculator in Hours
Add or subtract two times and get the answer as hours and minutes and as decimal hours, which is what invoices and payroll use.
Be the first to rate this tool
The formula
Decimal hours = hours + minutes / 60 + seconds / 3600.
Decimal hours explained
Decimal hours express minutes as a fraction of an hour: 15 minutes is 0.25, 30 minutes is 0.5, 45 minutes is 0.75. So 2 hours 15 minutes is 2.25 hours.
Quick conversion table
| Minutes | Decimal |
|---|---|
| 6 | 0.10 |
| 10 | 0.17 |
| 15 | 0.25 |
| 20 | 0.33 |
| 30 | 0.50 |
| 45 | 0.75 |
Billing example
You billed 3 hours 20 minutes on one job and 1 hour 50 minutes on another. Together that is 5 hours 10 minutes, or 5.1667 hours. At 60 an hour, the invoice is 310.
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 in Hours: frequently asked questions
Why does 20 minutes show as 0.33?
Because 20 divided by 60 is 0.3333 repeating. Most invoices round to two decimals.
Which is more accurate, hh:mm or decimal?
Both are exact here. Decimal is simply easier to multiply by a rate.
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