What the time calculator does
- Add / subtract time — combine any number of durations in days, hours, minutes and seconds, adding or subtracting each row.
- Time between two times — the hours and minutes from a start time to an end time, with an optional unpaid break and automatic overnight handling.
- Add to a clock time — find what the clock will read after adding or subtracting a duration, such as 9:30 AM plus 2 hours 45 minutes.
How to add and subtract time by hand
Work from the smallest unit up: add the seconds, carry every 60 seconds into a minute, then add the minutes and carry every 60 minutes into an hour. For example, 2 h 45 min + 1 h 30 min is 3 h 75 min, which carries to 4 h 15 min. Subtraction borrows the other way: 5 h 10 min − 2 h 35 min is 2 h 35 min, because 10 minutes borrows an hour to become 70 minutes.
Minutes to decimal hours
Payroll and billing systems usually want hours as a decimal. Divide the minutes by 60:
| Minutes | Decimal hours |
|---|---|
| 5 min | 0.08 h |
| 10 min | 0.17 h |
| 15 min | 0.25 h |
| 20 min | 0.33 h |
| 25 min | 0.42 h |
| 30 min | 0.5 h |
| 35 min | 0.58 h |
| 40 min | 0.67 h |
| 45 min | 0.75 h |
| 50 min | 0.83 h |
| 55 min | 0.92 h |
| 60 min | 1 h |
Common uses
- Timesheets and hours worked, including shifts that run past midnight
- Cooking, baking and recipe timings that need to be combined
- Video, audio and podcast running times
- Travel and flight durations and layovers
- Project and task time tracking
Frequently asked questions
How do I add hours and minutes together?
Add the minutes first; every 60 minutes carries over as one hour. Then add the hours. For example, 2 h 45 min + 1 h 30 min = 4 h 15 min. The calculator does this for any number of rows, including days and seconds.
How do I calculate hours worked between two times?
Open "Time between two times", enter the start and end times and any unpaid break. For example, 9:00 AM to 5:30 PM with a 30-minute break is 8 hours (8.0 decimal hours). If the end time is earlier than the start time, the calculator assumes the shift runs past midnight.
How do I convert minutes to decimal hours?
Divide the minutes by 60. For example, 15 minutes is 0.25 hours, 30 minutes is 0.5 hours and 45 minutes is 0.75 hours. The "Decimal hours" result shows this automatically.
Can I subtract time that goes back past midnight?
Yes. In "Add to a clock time", choose Subtract and enter the duration. For example, 1:00 AM minus 3 hours gives 10:00 PM, shown as the previous day.