Time Duration Calculator
This free time duration calculator finds how much time passes between a start time and an end time, in hours, minutes and seconds. It also handles shifts that cross midnight and gives the total in minutes and in seconds, which makes timesheets and billing much easier.
How to use the time duration calculator
- Enter the start time.
- Enter the end time.
- If the end time is on the next day, for example a night shift, choose Yes – end time is next day.
- Press Calculate Duration.
How the duration is calculated
Both times are turned into minutes after midnight and the start is subtracted from the end. When the period crosses midnight, 24 hours (1,440 minutes) are added to the end time first. The result is then split back into hours and minutes and also shown as a single total in minutes and seconds.
Worked examples
- A work day from 9:15 to 17:45 lasts 8 hours 30 minutes, which is 510 minutes or 8.5 hours.
- A night shift from 22:00 to 06:00 (next day) lasts 8 hours, or 480 minutes.
- A meeting from 14:10 to 15:35 lasts 1 hour 25 minutes, or 85 minutes.
Converting minutes to decimal hours
Payroll and invoicing systems usually want hours as a decimal number. Divide the minutes by 60: 15 minutes = 0.25 h, 30 minutes = 0.5 h, 45 minutes = 0.75 h, and 20 minutes ≈ 0.33 h. So 8 hours 45 minutes is entered as 8.75 hours. Multiply the decimal hours by your hourly rate to get the amount to bill.
When a time duration calculator is useful
- Filling in timesheets and checking overtime.
- Billing clients by the hour as a freelancer.
- Planning travel, layovers and how long a trip takes.
- Tracking study sessions, workouts, sleep or cooking times.
- Working out how long a call, recording or event lasted.
Frequently asked questions about the time duration calculator
Can it handle times that cross midnight?
Yes. Select the option that the end time is on the next day and 24 hours are added automatically.
Does it use 12-hour or 24-hour format?
It follows your device settings. On a 12-hour clock, make sure AM and PM are set correctly.
How do I subtract a lunch break?
Calculate the full period, then subtract the break. For example 8 h 30 min minus a 30-minute break is 8 hours of work.
Why do seconds show zero?
The time fields work in hours and minutes, which is enough for most uses, so the seconds part is usually zero.
Can I add up several durations?
Calculate each one and add the totals in minutes, then divide by 60 to get hours.
Minutes to decimal hours table
| Minutes | Decimal hours |
|---|---|
| 5 | 0.08 |
| 10 | 0.17 |
| 15 | 0.25 |
| 20 | 0.33 |
| 30 | 0.50 |
| 40 | 0.67 |
| 45 | 0.75 |
| 50 | 0.83 |
| 55 | 0.92 |
Tips for tracking time accurately
- Write down start and end times as you go instead of estimating at the end of the day.
- Round consistently, for example always to the nearest 5 or 15 minutes, especially when billing clients.
- Keep breaks separate so you can show worked time and paid time clearly.
- For overnight work, always note which day the shift ended to avoid counting 24 hours too few.
Related tools
- Date Difference Calculator – for periods longer than a day.
- Salary After Tax Calculator – turn hours into take-home pay.
- Age Calculator
- All free tools
Further reading: the 24-hour clock on Wikipedia.