UtilTools

Time Calculator

Add and subtract hours, minutes and seconds.

Time Calculator adds and subtracts durations in hours, minutes and seconds, sums a list of times such as timesheet entries, and works out the span between two clock times across midnight. It also converts a duration into decimal hours for billing. It runs offline in your browser.

Loading Time Calculator…

Runs entirely on your device. No file or text you enter here is uploaded. How to verify it.

How to use Time Calculator

  1. Choose add/subtract, sum a list, or span between two clock times.
  2. Enter the values in HH:MM:SS or as separate fields.
  3. Read the result and its decimal-hour equivalent.

Questions about Time Calculator

How do I total a week of timesheet entries?
Use the list mode and paste one duration per line, in 8:15 or 8h 15m form. The total appears in both HH:MM and decimal hours, which is what payroll systems expect.
What about a shift that crosses midnight?
The span mode detects it: 22:30 to 06:15 is calculated as 7 hours 45 minutes rather than a negative number.
Why does my decimal total look wrong?
Minutes are sixtieths, not hundredths. 8 hours 30 minutes is 8.5 decimal hours, but 8 hours 15 minutes is 8.25, not 8.15 — the most common payroll error there is.
What happens to a line it cannot read?
It is left out of the total and listed back to you in a warning, quoted exactly as you typed it. Nothing is silently counted as zero, which is the failure mode that makes a wrong timesheet look right.
Which duration formats does it accept?
Colon form such as 8:15 or 8:15:30, unit form such as 8h 15m, 90 min or 1.5h, and a bare number, which is read as minutes. Mixing formats down a pasted list is fine.
Is Time Calculator really free, with no limits?
Yes. There is no account, no daily cap, no file-size tier and no watermark, because there is no server cost to recover. The site is funded by clearly disclosed partner recommendations on the Partners page, never by metering the tools.
Are my files or text uploaded when I use Time Calculator?
No. Everything is processed by JavaScript running in your browser, on your device. You can verify it: open your browser's developer tools, switch to the Network tab, and use the tool. You will see no request carrying your data — because there is nowhere for it to go.