Time Duration Calculator

Calculate the duration between two times; intervals crossing midnight are supported.

e.g. 09:30

e.g. 17:45

Your result will appear here

Fill in the fields and press Calculate.

Finding the time between two clock times looks simple, but two things trip people up: minutes run in base 60 (1.5 hours is "1 hour 30 minutes," not "1.30"), and intervals that cross midnight. How long a shift ran, a flight's duration, the length of a break — all can hit these two traps.

Enter a start and end time (HH:MM), and the duration is calculated in hours and minutes, correctly even across midnight.

How is it calculated?

How it's calculated

Both times are converted to minutes (hours × 60 + minutes), the difference is taken, and it's converted back to hours and minutes. 09:30 = 570 minutes, 17:45 = 1,065 minutes; the difference is 495 minutes = 8 hours 15 minutes.

Intervals that cross midnight

If the end time is earlier than the start (e.g. 22:00 to 06:00), the interval has crossed midnight; 24 hours are added to the end. So 22:00 → 06:00 is not −16 hours but 8 hours. This is the most common mistake in night shifts and flights.

Time is not decimal

The most frequent confusion: 1 hour 30 minutes is "1.5 hours," but writing 1 hour 30 minutes as "1.30" and adding is wrong. 90 minutes = 1.5 hours; you convert to decimals by dividing minutes by 60. That matters wherever decimals are needed, such as pay calculations.

Common uses

  • Work/shifts: hours worked (including night shifts).
  • Flights/travel: elapsed time between two clock times (same time zone).
  • Breaks/events: how long an activity lasted.

For durations spanning different DAYS, a days-between or days-until calculator is the right tool; this one is for same-day (or single overnight) time intervals.

Worked example

A shift from 09:30 in the morning to 17:45 in the evening: 09:30 = 570 minutes, 17:45 = 1,065 minutes; the difference is 495 minutes = 8 hours 15 minutes (subtract any break separately). For a night shift starting at 22:00 and ending at 06:00: since the end is earlier than the start, midnight has been crossed, 24 hours are added to the end, and the duration comes out as 8 hours — subtracting "06:00 minus 22:00" directly would give the wrong answer.

FAQ

How do I calculate the duration between two times?+

Both times are converted to minutes, the difference is taken, and it's converted back to hours and minutes. 09:30 to 17:45 is 495 minutes, or 8 hours 15 minutes.

How is a duration across midnight calculated?+

If the end time is earlier than the start, midnight has been crossed and 24 hours are added to the end. So 22:00 → 06:00 is calculated as 8 hours. The tool does this automatically.

Why is 1 hour 30 minutes 1.5 hours and not 1.30?+

Time is base 60, not decimal. 30 minutes is half an hour, so it equals 0.5: 1 hour 30 minutes = 1.5 hours. You convert minutes to decimals by dividing by 60.

Can I calculate a shift length with this?+

Yes — enter the start and end time and it gives the duration, including night shifts. Subtract break time from the result separately.

Does it handle two times on different days?+

This tool is for same-day or single-overnight intervals. For durations spanning multiple days, use a days-between-dates calculator.

Does it show the time-zone difference between cities?+

No — this tool finds the duration between two clock times, not the UTC offset between time zones. City-to-city time-zone differences are a separate matter.