How the time calculator works
- Time between: enter a start and end time. If the end is earlier on the clock, it is treated as the next day. Add extra full days for longer spans.
- Add to a time: start from a clock time and add or subtract hours and minutes. The result shows the new time and whether it falls on the next or previous day.
- Add durations: list hours, minutes, and seconds and choose to add or subtract each one. Units carry over automatically at 60.
Formulas
Times that cross midnight follow the add-24-hours rule explained in how to calculate overnight shift hours.
Worked examples
Time between 8:45 AM and 5:15 PM
- On a 24-hour clock: 17:15 − 08:45.
- Borrow an hour: 16:75 − 08:45 = 8 hours 30 minutes, or 8.50 hours.
Add 9 hours 45 minutes to 10:30 PM
- 22:30 + 9:45 = 31:75, which is 32:15.
- Subtract 24 hours: 8:15 AM the next day.
Add 3 h 54 m 46 s and 19 h 33 m 55 s
- Seconds: 46 + 55 = 101 s = 1 m 41 s.
- Minutes: 54 + 33 + 1 = 88 m = 1 h 28 m.
- Hours: 3 + 19 + 1 = 23 h. Total: 23 h 28 m 41 s.
Minutes reference
| Duration | Minutes | Seconds | Decimal hours |
|---|---|---|---|
| 15 min | 15 | 900 | 0.25 |
| 30 min | 30 | 1,800 | 0.50 |
| 45 min | 45 | 2,700 | 0.75 |
| 1 h | 60 | 3,600 | 1.00 |
| 1 h 30 min | 90 | 5,400 | 1.50 |
| 2 h | 120 | 7,200 | 2.00 |
| 4 h | 240 | 14,400 | 4.00 |
| 8 h | 480 | 28,800 | 8.00 |
| 12 h | 720 | 43,200 | 12.00 |
| 24 h | 1,440 | 86,400 | 24.00 |
Assumptions
- Clock times are whole minutes on a 24-hour day. Daylight saving changes and time zones are not applied.
- Equal start and end times are read as a full 24 hours in "Time between" mode.
- Durations accept whole hours, and minutes and seconds from 0 to 59.
Tracking work time? The work hours calculator subtracts breaks, and the time card calculator adds overtime and pay.
Frequently asked questions
How do I find the time between two times?
Convert both times to a 24-hour clock and subtract. If the end time is earlier, add 24 hours first because it is on the next day. For example, 10:30 PM to 2:15 AM is (2:15 + 24:00) − 22:30 = 3 hours 45 minutes.
How do I add hours to a time?
Add the hours and minutes, carrying 60 minutes into an hour. If the result passes midnight, subtract 24 hours and note that it is the next day. For example, 10:30 PM plus 9 hours 45 minutes is 8:15 AM the next day.
How do I add up hours, minutes, and seconds?
Add each unit separately, then carry: every 60 seconds becomes a minute and every 60 minutes becomes an hour. The “Add durations” mode does this for as many rows as you need, and you can subtract rows too.
Can the result be negative?
In “Add durations” mode, yes. If you subtract more time than you add, the result is shown with a minus sign.
Does it handle dates or time zones?
No. This calculator works with clock times and durations only. Use “Extra full days” for spans longer than a day. It does not adjust for daylight saving changes or time zones.
Related guides
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How this calculator was built. The formula, defaults, and edge cases are documented in a research record and covered by automated tests. It estimates gross amounts from your inputs; it does not determine legal entitlements, taxes, or take-home pay. Read our methodology and disclaimer.
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