Time Duration Calculator
Find the elapsed time between two times of day. Returns hours and minutes, decimal hours, total minutes, and flags whether the duration crosses midnight.
Duration
8h 15m
- Decimal hours
- 8.25
- Total minutes
- 495
- Total seconds
- 29,700
- Crosses midnight
- No
09:15 to 17:30 on the same day.
How to use this calculator
Enter the start hour and minute using the 24-hour clock — so 9:15 AM is 9 and 15, while 5:30 PM is 17 and 30. Do the same for the end time. The calculator returns the duration in hours and minutes, decimal hours, and total minutes and seconds. If the end time is earlier than the start time, the calculator assumes the end is on the following day and adds 24 hours automatically — useful for night shifts, sleep, and overnight bookings.
How the calculation works
Each time is converted to minutes past midnight (hours × 60 + minutes). The duration is the end minutes minus the start minutes. When the end is earlier than the start — for example 22:00 to 06:30 — the calculator adds 1440 minutes (one full day) to the end so the result stays positive. This is the same convention used by Google's answer box, calculator.net, and most payroll systems. The hour-and-minute breakdown is the quotient and remainder of the total minutes divided by 60.
Worked example
A typical office day: start 09:15, end 17:30. Start = 9 × 60 + 15 = 555 minutes. End = 17 × 60 + 30 = 1050 minutes. Duration = 1050 − 555 = 495 minutes = 8 hours 15 minutes = 8.25 decimal hours. A night shift: start 22:00, end 06:30 (next morning). Start = 1320, end = 390. Because 390 < 1320, the calculator adds 1440: end = 390 + 1440 = 1830. Duration = 1830 − 1320 = 510 minutes = 8 hours 30 minutes = 8.5 decimal hours.
Frequently asked questions
How do I enter times after noon?
Use the 24-hour clock. 1:00 PM is 13:00, 5:30 PM is 17:30, and 11:45 PM is 23:45. Midnight at the start of the day is 00:00 and midnight at the end of the day is 24:00 (which you would enter as the start of the next day, 00:00, and tick "next day" implicitly by setting an earlier end time). The 24-hour clock is unambiguous and avoids AM/PM confusion — the same convention used by ISO 8601, aviation, the military, and almost every European country in everyday life.
What happens when the end time is earlier than the start time?
The calculator assumes the end is on the following day and adds 24 hours. So 22:00 to 06:30 returns 8 hours 30 minutes, not minus 15 hours 30 minutes. This matches how people actually talk about overnight shifts, sleep, and overnight trips. If you genuinely want to find how much time has elapsed since an earlier time on the same day, swap the start and end values.
Why do I get a decimal hours result like 8.25?
Decimal hours are the format used by most payroll, time-tracking, and freelance billing systems. 8 hours 15 minutes is 8.25 decimal hours because 15 minutes is a quarter of an hour. Other common conversions: 30 minutes is 0.50 hours, 45 minutes is 0.75 hours, 10 minutes is 0.167 hours, and 6 minutes is exactly 0.10 hours. If you bill in 6-minute increments, the decimal hours value is what goes on the invoice.
Can it handle durations longer than 24 hours?
No, this calculator finds the duration between two times of day within at most one calendar day (or one midnight crossing). For durations measured in days, weeks, or longer, use the days-between-dates calculator, which takes full dates rather than just times. The two calculators are designed for different jobs — this one is optimised for shifts, meetings, and same-or-next-day spans.
Does the calculator handle seconds?
The output includes total seconds as a breakdown row, but inputs are limited to hours and minutes. For most real-world use cases — shift work, billing, cooking timers, meeting lengths — minute precision is enough. If you need second-level precision (timing a race, measuring a callout), a stopwatch or video-frame timer is more appropriate than a calculator working from two clock readings.
Is the math affected by daylight saving time?
No. The calculator operates on raw clock readings, not actual elapsed wall-clock time. On the day a country switches into DST, an hour disappears from the clock between 02:00 and 03:00 (in most regions); on the switch out, an hour repeats. If your start and end straddle a DST transition, you may need to add or subtract one hour to get the real elapsed duration. For ordinary days — which is almost every day of the year — the clock-time result is identical to the elapsed time.