Add hours and minutes
Adding 3:45 and 2:30 on an ordinary calculator gives 6.75, which is wrong: minutes go up to 60, not 100. Enter one duration per line and get the correct total, the decimal hours that payroll needs and the amount to invoice.
- Decimal hours
- 7.17
- Total minutes
- 430
- Days · hours
- 0 · 7:10
- Entries
- 4
- Average per entry
- 1:47:30
- Amount at that rate
- —
The formula
Every entry is converted to seconds, the seconds are added, and the total is written back as hours:minutes:seconds. Decimal hours = seconds ÷ 3600, so 7 h 10 min = 7.17 h. A minus sign subtracts a line, for a break or a correction.
Worked example
3:45 + 2:30 + 1:15 − 0:20 = 7:10, which is 7.17 decimal hours or 430 minutes. At 20 an hour that is 143.33.
How to use it
- 1Write one duration per line, or separate them with commas or a plus sign.
- 2Use 1:30, 1h30, 90m or 45s; add seconds as 1:15:30.
- 3Put a minus sign in front of breaks or corrections to subtract them.
Questions people ask
How do I turn minutes into decimal hours?
Divide by 60. 15 minutes is 0.25, 30 is 0.5, 45 is 0.75, and 10 minutes is 0.17. Payroll and invoicing software expect decimal hours, which is why the figure is shown separately.
Can the total go over 24 hours?
Yes. The total keeps counting hours, so a week of timesheets can show 38:30. The days and hours line splits it into whole days of 24 hours as well.
Last reviewed: 2026-10-23