What is the Time Calculator?
The time calculator does the three time sums people struggle with: adding and subtracting durations (2 h 45 m + 1 h 30 m), finding the duration between two times (9:00 to 17:30), and adding a duration to a clock time (8:00 + 9 h 30 m).
It understands that 60 minutes make an hour and handles periods that cross midnight, so it works for night shifts and long journeys. For weekly timesheets with breaks and overtime, use the Working Hours Calculator.
How to use the Time Calculator
- Use Add or subtract time to combine durations.
- Use Duration between two times to find how long a shift or trip lasts.
- Use Add duration to a clock time to find an end time.
- Results show hours, minutes, seconds and decimal hours.
Example
2 h 45 m + 1 h 30 m = 4 h 15 m (4.25 decimal hours). A shift from 22:00 to 06:30 lasts 8 h 30 m even though it crosses midnight.
Converting minutes to decimal hours
| Minutes | Decimal hours |
|---|---|
| 15 | 0.25 |
| 20 | 0.33 |
| 30 | 0.5 |
| 40 | 0.67 |
| 45 | 0.75 |
Why time maths is tricky
Time uses base 60, not base 10, so 1.5 hours is 1 hour 30 minutes, not 1 hour 50 minutes. Payroll systems often need decimal hours, which is why the calculator shows both formats.
You may also need
People who use the Time Calculator often need these related tools too:
- Time Zone Converter: See the same moment in Pakistan, the Gulf, the UK, the USA and anywhere else, with working-hours colours and automatic daylight saving.
- Date & Time Difference: Get the exact time between two date-times, each in its own time zone, in days, hours, minutes and seconds.
Frequently asked questions
How do I add hours and minutes?
Add the minutes and hours separately; every 60 minutes carries over as one hour. The calculator does this for you.
How do I calculate time between two times?
Use the duration calculator. Enter the start and end time; if the end is earlier, it assumes the period runs past midnight.
How do I convert minutes to decimal hours?
Divide the minutes by 60. 45 minutes is 0.75 hours.
Can I subtract time?
Yes. Choose "Subtract" to take one duration away from another.
Does it work with 12-hour times?
The time inputs follow your device setting. To convert formats use the 12h / 24h / Military Time Converter.
Is the Time Calculator free to use?
Yes. The Time Calculator on Custom Converter is completely free, with no sign-up, no daily limit and no watermark.
Does the Time Calculator work on mobile phones?
Yes. It is built mobile-first and works on Android phones, iPhones, tablets and computers in any modern browser, with no app to install.