⏱️ Time Calculator
Add or subtract hours, minutes and seconds, add time to a clock time, or find the time between two times — with totals in decimal hours.
Minutes and seconds carry over automatically: 90 minutes is shown as 1:30:00. Decimal hours use 60 minutes = 1.0, so 1 hour 15 minutes = 1.25 hours.
What Time Calculator Does
This time calculator does the three time sums people most often need, on one page: add or subtract a list of durations (2 h 45 min + 1 h 30 min), add hours and minutes to a clock time (what time is it 7 h 50 min after 9:15 PM?), and find the time between two clock times, including shifts that run past midnight.
Every total is shown in hours and minutes and also as decimal hours, which is what timesheets and payroll use: 7 hours 45 minutes is 7.75 hours. Time is base 60, so ordinary calculators give the wrong answer — 1.45 + 1.30 = 2.75, while 1 h 45 min + 1 h 30 min is really 3 h 15 min.
How to Use Time Calculator
- Choose Add or subtract times, Clock time ± hours, or Time between two times
- Enter hours, minutes and seconds (or clock times)
- Add more rows or switch rows to subtract
- Read the total in h:mm:ss, decimal hours, minutes and seconds
Formula Used by Time Calculator
Adding durations
Total minutes = Σ (hours × 60 + minutes) · Hours = ⌊total ÷ 60⌋ · Minutes = total mod 60
Worked example
2 h 45 min + 1 h 30 min
- 165 + 90 = 255 minutes
- 255 ÷ 60 = 4 remainder 15
Result: 4 h 15 min, or 4.25 hours.
Time between two clock times
Duration = end − start; if the end is earlier on the clock, add 24 hours
Worked example
A shift from 10:30 PM to 6:15 AM.
- 22:30 → 06:15
- 6:15 − 22:30 = −16 h 15 min
- −16 h 15 min + 24 h
Result: 7 h 45 min, or 7.75 hours.
Minutes to Decimal Hours
Decimal hours = minutes ÷ 60.
| Minutes | Decimal hours | Minutes | Decimal hours |
|---|---|---|---|
| 5 | 0.083 | 35 | 0.583 |
| 10 | 0.167 | 40 | 0.667 |
| 15 | 0.25 | 45 | 0.75 |
| 20 | 0.333 | 50 | 0.833 |
| 25 | 0.417 | 55 | 0.917 |
| 30 | 0.5 | 60 | 1.0 |
How to Read Your Result
Timesheets
Payroll usually multiplies decimal hours by the hourly rate: 7.75 hours at $20 is $155. Some employers round to the nearest quarter hour or tenth of an hour, so the pay on your stub can differ from an exact total by a few minutes.
Crossing midnight
When you add hours to a clock time, the result notes how many days later it lands, so a 9:15 PM start plus 7 h 50 min shows 5:05 AM the next day.
Limitations & Accuracy Notes
- Clock-time sums assume a 24-hour day and do not adjust for daylight saving time changes, when a local day is 23 or 25 hours long.
- Duration lists accept seconds; decimal hours are rounded to four places.
- For differences between calendar dates, use a date calculator.