The formula
How it works
Measure the exact length of time between two moments — down to the minute. Enter a start and end date and time, and the calculator breaks the duration into days, hours and minutes, and totals it in each unit.
FAQ
Can the two points be on different days?
Yes. Enter separate start and end dates as well as times, and the calculator spans as many days as needed, so it works for anything from a few minutes to months apart.
What if I only care about times, not dates?
Set both dates to the same day and just change the times. The calculator then measures the gap within that day, which is handy for working hours, cooking times or event lengths.
Does it account for time zones?
No, both the start and end are treated as being in the same local time, so if your two moments are in different time zones you will need to convert one of them to match before entering it.
Does it handle daylight saving changes?
The calculation is based on the calendar dates and clock times you enter, not on your device clock, so it will not automatically add or remove the hour that shifts on a daylight-saving change.
What does a negative duration mean?
It means the end date and time you entered comes before the start, which is usually a sign the two have been swapped by mistake — check the order of your inputs.
Can it show the result in weeks or seconds?
The breakdown covers days, hours and minutes, plus totals in hours and minutes. To get weeks, divide the total days by 7; for seconds, multiply the total minutes by 60.
How precise is the result?
It is precise to the minute, based on the exact times you enter — it does not account for seconds, so very short intervals under a minute will round to zero.
About the time duration calculator
This calculator measures the exact amount of time between two points, each given as a date and a time. Working out a duration that crosses midnight, or spans several days, is fiddly to do by hand because hours and minutes do not fit neatly into a decimal system. By handling real dates and clock times together, the calculator gives a precise result and expresses it in whatever unit is most useful.
How to use it
Enter the start date and time, then the end date and time. The calculator returns the duration broken into days, hours and minutes, plus the totals in hours and minutes on their own. For example, from 9:00 on 1 January to 14:30 on 3 January is 2 days, 5 hours and 30 minutes — or 53.5 hours in total. If the end is before the start, the duration is shown as negative to flag the mistake.
The formula
The duration is simply the end moment minus the start moment, . Each date-and-time is converted to a single running count of minutes (or milliseconds), the two are subtracted, and the difference is then split back into days, hours and minutes. Because the calculation happens on real timestamps, days of different lengths around clock changes and month boundaries are all handled correctly.
Where it is used
People use it to time events, track how long a task or journey took, and work out shift and project durations that run across days. It is handy for logging billable time, measuring cooking or reaction times, and counting down to a deadline given to the minute. Wherever the precise gap between two timestamps matters, this turns two clock readings into a clear, usable duration.