Time Duration Calculator — Calculate Elapsed Time Between Two Times
Calculate time between two dates, add days and hours to a date, and see duration in days, weeks, business days, and HH:MM:SS.
Find the exact elapsed time between two moments — in years, months, days, hours, minutes, and seconds.
Times use your device timezone. For GMT/UTC conversion between cities, use the time zone converter.
About this tool
The Time Duration Calculator finds the exact time elapsed between any two dates and times. Enter a start time and end time and get the difference in days, hours, minutes, and seconds instantly. Useful for billing hours worked, calculating project durations, measuring event lengths, or finding age in days.
Unlike mental arithmetic, this tool handles midnight crossovers, month-end boundaries, leap years, and multi-day spans automatically.
How to use
- Enter the start date and time.
- Enter the end date and time.
- The tool shows the elapsed duration broken down into days, hours, minutes, and seconds.
- For time-only calculations (same day), just enter the times without dates.
This page is available at /tools/time-duration-calculator/.
Understanding the result
- Duration is always positive — the tool handles cases where end time is the next day automatically.
- For billing purposes, round up to the nearest quarter hour (15 minutes) or the unit your contract specifies.
- For multi-day durations, note whether the count includes or excludes the start and end days — this matters for legal deadlines.
- Leap years are handled automatically — February 29 is counted correctly.
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FAQ
How do I calculate elapsed time that crosses midnight?
Enter the full date and time for both start and end, not just the time. For example, start: 2024-01-15 22:00 and end: 2024-01-16 06:00 gives 8 hours correctly, whereas time-only subtraction would give a negative result.
Can I calculate time duration in decimal hours for billing?
Most billing uses decimal hours. 1 hour 30 minutes = 1.5 hours. 1 hour 45 minutes = 1.75 hours. Divide the minutes by 60 and add to the hours.
What is the difference between elapsed time and duration?
They mean the same thing: the amount of time that passes between a start point and an end point. Elapsed time emphasises that time has already passed; duration is often used for future planning.
How many working days are between two dates?
This calculator shows total calendar days. To exclude weekends, subtract the number of weekend days in the range. For exact working days with holidays, use a dedicated business days calculator.