The time duration calculator finds elapsed hours and minutes between two clock times. It supports overnight periods so an evening start and morning end can be measured correctly when the end belongs to the next day.
How to use this calculator
Enter the start and end times in 24-hour format. If the end is on the following calendar day, select the next-day option. Without that option, both times are treated as belonging to the same day.
Formula & calculation method
Duration = end minutes − start minutes, plus 1,440 minutes when next day is selectedEach time is converted to minutes after midnight. The difference is separated into whole hours and remaining minutes, and decimal hours are also shown for timesheets or billing calculations.
Worked example
A period from 22:00 to 06:30 with next day selected is 8 hours 30 minutes. The same entries without the option represent a negative same-day interval and are rejected.
Why this is useful
The overnight option avoids a common error in shift and travel calculations. Decimal hours complement the hours-and-minutes result when a payroll or billing system expects decimal input.
Limitations to keep in mind
The calculator measures clock duration only. It does not deduct breaks, determine overtime, or account for daylight-saving transitions because no date or time zone is supplied. Add those details separately when relevant.
Frequently asked questions
How do I calculate an overnight shift?
Enter the evening start and morning end, then select the next-day checkbox so 24 hours are added to the end time.
Does it subtract breaks?
No. Calculate the gross duration first, then subtract unpaid break time according to your schedule or payroll rules.
Why are decimal hours included?
They are convenient for billing and timesheets. For example, 1 hour 30 minutes equals 1.5 decimal hours.