A standard workday: 09:00 to 17:30
- Input
- Start = 09:00, End = 17:30
- Working
- 17:30 is 1,050 minutes since midnight; 09:00 is 540. 1,050 − 540 = 510 minutes = 8 h 30 min = 8.5 decimal hours.
- Result
- 8 h 30 min (510 minutes, 8.5 h)
Time Duration Calculator
Work out the time between two clock times — shifts, flights, study sessions — with overnight spans handled, in hours and minutes, decimal hours and total minutes. Runs entirely in your browser — your numbers never leave this device.
Duration
7 h 45 min
22:30 → 06:15 runs past midnight, so the end is read as next-day.
- Total minutes
- 465
- Decimal hours
- 7.75
- In hours and minutes
- 7 h 45 min
- Overnight span?
- Yes — crosses midnight
Convention: when the end time is earlier than the start time, the span is treated as running overnight into the next day (22:30 → 06:15 = 7 h 45 min). Identical start and end times give 0 — a zero-length span, not 24 hours.
How it works
Duration = end time − start time, in minutes since midnight | If the end is earlier than the start, add 24 h (the span runs overnight) | Equal times = 0
| Start | End | Duration | Decimal hours |
|---|---|---|---|
| 09:00 | 17:30 | 8 h 30 min (510 min) | 8.5 |
| 22:30 | 06:15 | 7 h 45 min (465 min) — overnight | 7.75 |
| 09:00 | 19:00 | 10 h (600 min) | 10 |
| 09:00 | 09:00 | 0 min — equal times | 0 |
Enter a start and an end time and the calculator converts both to minutes since midnight and subtracts. The answer is presented three ways, because different jobs want different forms: hours and minutes for humans, total minutes for logs and timesheets, and decimal hours for billing and payroll, where 7 h 45 min must become 7.75 before it can be multiplied by an hourly rate.
The one convention to know is the overnight rule: when the end time is earlier than the start time, the span is read as running past midnight into the next day — 22:30 to 06:15 is 7 hours 45 minutes, the classic night shift. Without that rule every overnight span would come out negative or would need a date attached, and night workers would be the ones doing mental arithmetic. Equal start and end times are zero, not 24 hours: a duration measures elapsed time, and no time elapses between a moment and itself.
For spans longer than a day, or spans between two different dates, this is the wrong tool on purpose — pair the dates in the Days Between Dates calculator and add the clock-time remainder from here. Everything computes in your browser.
Worked examples
A night shift: 22:30 to 06:15
- Input
- Start = 22:30, End = 06:15
- Working
- 06:15 (375 min) is earlier than 22:30 (1,350 min), so the span runs overnight: 375 + 1,440 − 1,350 = 465 minutes = 7 h 45 min = 7.75 decimal hours.
- Result
- 7 h 45 min (465 minutes, 7.75 h)
A long day: 09:00 to 19:00
- Input
- Start = 09:00, End = 19:00
- Working
- 1,140 − 540 = 600 minutes — exactly 10 hours, the gross length of the long Thursday in the Time Card example week.
- Result
- 10 h (600 minutes)
Frequently asked questions
How are overnight times handled?
If the end time is earlier than the start time, the calculator assumes the span crosses midnight and adds 24 hours to the end before subtracting: 22:30 → 06:15 becomes 7 h 45 min. If your span really is same-day backwards (a data entry error, usually), the convention note under the result warns you.
Why do equal start and end times give 0 and not 24 hours?
Because a duration is elapsed time between two moments, and a moment minus itself is zero. Treating it as 24 h would make every typo'd same-time entry produce a phantom full day on a timesheet. If you genuinely worked a full 24 h span, split it at midnight and add the two halves, or log it in the Hours Calculator as 24:00.
What are decimal hours for?
Payroll and billing multiply time by a rate, and rates do not multiply '7 h 45 min' — they multiply 7.75. The conversion is minutes ÷ 60: 45 minutes is 0.75 of an hour, 510 minutes is 8.5 hours. Beware the common mistake of reading 7:45 as 7.45 hours; that underpays by 18 minutes.
Can this measure a span longer than 24 hours?
Not directly — it works on clock faces, so spans wrap at a day. For multi-day spans, count the whole days with the Days Between Dates calculator and the leftover clock time here, then add them: 2 days + 3 h 15 min is an exact answer.
How do I subtract a break from the duration?
For a single day, subtract the break from the total minutes (510 − 30 = 480 for a standard day with a half-hour break). For a whole week of shifts with breaks, the Time Card Calculator does this per day and totals regular and overtime hours for you.
Is anything I enter uploaded?
No. The times are processed in your browser only — nothing is sent to a server or stored.
Related tools
Hours Calculator◷Add up a list of hours and durations — timesheet entries, study sessions, project time — in mixed formats, with a running total and decimal hours for payroll.Open tool →Time Card Calculator◷Total a week of clock-in and clock-out times with unpaid breaks deducted per day, and split the week into regular hours and overtime past 40.Open tool →Days Between Dates Calculator◷Count the calendar days and business days between two dates, with the end-date convention stated openly and a weeks-and-days breakdown alongside.Open tool →Stopwatch & Timer◷A free online stopwatch with laps and a countdown timer on one page — no app, no sign-up — timed from your device clock to a tenth of a second.Open tool →
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