How to Use
- Enter the start time
Input the starting time in hours and minutes.
- Enter the end time
Input the ending time in hours and minutes.
- View the result
Click Calculate to see the elapsed time displayed in multiple units.
What is elapsed time?
Elapsed time is the amount of time that passes between a start time and an end time. Unlike a 'point in time' shown on a clock, it expresses the difference between two times as a 'duration' measured in hours, minutes, and seconds.
Why calculate it separately
Time is rounded in base 60 (60 seconds = 1 minute, 60 minutes = 1 hour), so simply subtracting 09:00 from 17:30 can be confusing. This is especially tricky for shifts that cross midnight, such as a night shift starting at 22:00 and ending at 06:00, where a plain subtraction gives a negative number.
Common uses
- Work & payroll — calculating daily working hours from clock-in and clock-out times
- Night & shift work — late-night tasks, hospital on-call, and other shifts crossing midnight
- Travel & activity — departure-to-arrival time, exercise duration, and sleep length
Calculation formula
Convert each time into 'total seconds' from midnight, then take the difference.
elapsed seconds = (total seconds of end time) − (total seconds of start time)
If the result is negative, midnight was crossed, so add one day (86,400 seconds): elapsed seconds + 86400. The conversions used are 1 hour = 3,600 seconds, 1 minute = 60 seconds.
Example — 09:00:00 → 17:30:00: end 63,000 s − start 32,400 s = 30,600 s → 30600 ÷ 3600 = 8 hours, remainder 1,800 ÷ 60 = 30 minutes, 0 seconds → 8 h 30 m. Crossing midnight — 22:00 → 06:00: 21,600 − 79,200 = −57,600 → +86,400 = 28,800 seconds (8 hours).