Calculate Time Duration Calculator
Find the time between two clock times — even across midnight — or add and subtract durations for timesheets, shifts, and projects.
Time between two times
| Total minutes | — |
| Decimal hours | — |
Add / subtract durations
How it works
Between-times math converts both clock times to minutes since midnight; if the end time is earlier than the start, a full day (1,440 minutes) is added — that handles overnight shifts automatically. Duration arithmetic works in total minutes and converts back to hours and minutes.
Formula & worked example
Formula: Both times are converted to minutes since midnight (hours × 60 + minutes) and subtracted; if the end time is earlier than the start, 1,440 minutes (24 hours) are added so overnight spans work. Durations can also be added to and subtracted from each other directly.
Worked example: From 9:15 AM to 5:45 PM: 1,065 − 555 = 510 minutes, which is 8h 30m — 8.50 hours in decimal form.
When to use this
- A timesheet needs the length of a shift, including one that runs past midnight.
- You bill or are paid by the hour and need decimal hours, not hours and minutes, for the invoice or payroll form.
- Breaks, meetings and tasks with separate durations need adding together or netting off.
- Mental clock arithmetic across noon or midnight keeps giving you an answer you do not trust.
How to use it, step by step
- Enter the start and end times in the between-times section; there is no calculate button, it updates as you change them.
- If the end time is earlier than the start, the tool assumes the span crosses midnight and adds a day.
- Read the duration three ways: hours and minutes, total minutes, and decimal hours.
- For separate durations, use the add and subtract section below — for example, a shift minus its unpaid break.
- Chain the add and subtract section by feeding a result back in as Duration 1 when you have more than two pieces.
What the inputs mean
| Input | What it is | Typical values |
|---|---|---|
| Start time and end time | The two clock times bounding the span, within one day or across midnight | Shift starts and finishes, most often |
| Duration 1 and Duration 2 | Two lengths of time in hours and minutes, for the add and subtract section | Breaks, tasks, meetings, travel legs |
Another worked example
A night shift from 10:30 PM to 7:15 AM: the end time is earlier than the start, so the tool adds a full day before subtracting, and the shift comes out at 525 minutes — 8h 45m, or 8.75 hrs in the decimal form payroll wants. Without that overnight handling the same two times would produce a negative answer, which is exactly the error this calculation exists to prevent.
Frequently asked questions
Does it handle overnight shifts?
Yes. A shift from 22:00 to 06:00 correctly returns 8 hours — end times earlier than the start are treated as the next day.
What are decimal hours for?
Payroll and billing usually use decimal hours: 8 hours 15 minutes = 8.25 hours. The converter gives you both formats.
Can I add more than two durations?
Add the first two, then use the result as Duration 1 with the next duration — or tally weekly hours in our freelance rate calculator.
What happens if the start and end times are exactly the same?
The result is 0h 00m — zero minutes, 0.00 hrs. The tool only adds a day when the end is strictly earlier than the start, so identical times mean no time passed, not a 24-hour span. If you genuinely worked a full day, enter the two halves of it separately and add them.
How do I take an unpaid break out of a shift?
First read the full shift length from the between-times section, then use the subtract section with the shift as Duration 1 and the break as Duration 2. Taking a 45-minute break out of the 8h 45m night shift above leaves 8h 00m — the figure that belongs on the timesheet.
⏱️ Billing by the hour?
Turn those hours into a rate with the freelance hourly rate calculator, or convert wages with the hourly-to-salary converter.