Time Duration Calculator
A shift starts at 22:00 and ends at 06:45 the next morning. How long is it, and what happens if you subtract a 30 minute break? This calculator compares two clock times, rolls over midnight when needed, subtracts optional break minutes and returns the net duration as HH:MM, decimal hours, minutes and seconds.
How the duration is measured
-
1
Enter start and end times
Use 24 hour clock times such as 09:00, 17:30 or 22:00.
-
2
Add break minutes
Enter unpaid or excluded break time so the result shows the net working duration.
-
3
Handle midnight rollover
If the end time is earlier than the start time, the calculator treats it as the next day.
-
4
Copy the totals
Use HH:MM, decimal hours, total minutes or total seconds in payroll, invoices or spreadsheets.
Common uses
- Payroll: calculate the net length of a shift after unpaid breaks.
- Billing: convert precise clock intervals into decimal hours for invoices (8:45 = 8.75 hours).
- Travel planning: compare departure and arrival times after you have converted them to the same time zone.
- Project tracking: see how long a focused work session actually took.
- Cooking and fermentation: time an overnight prove, steep or rest from one clock time to another.
Decimal hours for billing
Most invoicing software wants hours as decimals, not h:mm. Conversion:
| h:mm | Decimal hours |
|---|---|
| 0:15 | 0.25 |
| 0:30 | 0.50 |
| 0:45 | 0.75 |
| 1:30 | 1.50 |
| 7:45 | 7.75 |
| 8:30 | 8.50 |
Midnight rollover logic
If you enter 22:00 as the start and 06:45 as the end, the calculator assumes the end time is on the next day and returns an elapsed time of 08:45 before breaks. With a 30 minute break, the net duration is 08:15.
If you meant a same-day interval, choose an end time later than the start time. For anything longer than one overnight span, split the period or use a date-aware duration calculator.
Subtle gotchas
- Timezone-naive. This tool treats both times as local clock times in the same time zone. Convert travel times before comparing them.
- Daylight saving transitions can change real elapsed time. A shift from 01:00 to 04:00 on a spring-forward night may be 2 real hours, not 3.
- Leap seconds are ignored, as they are in everyday payroll and spreadsheet workflows.
Exporting
The decimal-hours, total-minutes and total-seconds outputs are formatted for clean paste into Excel, Google Sheets, Notion or a payroll system. Copy the value that matches the field you need.
Frequently Asked Questions
No. This calculator is for one clock interval, including a simple overnight rollover. For multi-day spans, split the work into separate intervals or use a date-aware duration tool.
Enter the break length in minutes. The calculator subtracts it from the elapsed time and shows the net duration for payroll or billing.
The calculator is timezone-naive. It treats both times as being in the same unspecified timezone. If you mix UTC and PST without converting first, the result will be off by the timezone offset.
No. Everything runs in your browser.
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