Time Duration Calculator
Calculate a time duration
Work out the duration between two dates and times
This time duration calculator helps you measure the difference between a start date and time and an end date and time. It is useful for planning schedules, estimating how long an activity will take, and checking gaps between appointments or events.
Enter your start date and time and your end date and time, then click Calculate. The result shows the duration in a human-friendly breakdown (days, hours, minutes) as well as totals (total minutes, total hours, total seconds) so you can use it in planning or reporting.
If your end time is earlier than your start time, the calculator will show an error. This keeps the output unambiguous for normal planning use.
Assumptions and how to use this calculator
- Use the format YYYY-MM-DD HH:MM (24-hour time), for example 2025-12-12 09:30.
- You can also paste YYYY-MM-DDTHH:MM (the common “datetime-local” format), for example 2025-12-12T09:30.
- Results are calculated based on your device’s local time zone.
- This calculator measures exact elapsed time. It does not exclude weekends or business hours.
Common questions
Why does it say my date/time format is invalid?
The calculator accepts YYYY-MM-DD HH:MM or YYYY-MM-DDTHH:MM. Make sure you include leading zeros (for example, 09:05) and use a 24-hour clock.
Does this include daylight saving time changes?
The calculation uses your device’s local time rules. If your time zone applies daylight saving time and the range crosses a change, the elapsed time will reflect that.
Can I calculate the duration across multiple days?
Yes. The output includes a days, hours, and minutes breakdown, plus totals, even if the duration spans many days or weeks.
Why do I see a negative duration?
You should not. If the end time is earlier than the start time, the calculator shows an error so you can correct the inputs.
What is “total seconds” used for?
Total seconds and total minutes are useful for exporting into spreadsheets, timesheets, or other tools that expect a single number rather than a days and hours breakdown.