Calculate the exact duration between two dates and times, or find a future/past date/time by adding a duration.
Enter a start and end date-time below to get the exact duration between them in days, hours, minutes and seconds — accurate down to the second, unlike a simple date-only calculator. Use the second tool to add or subtract a duration from a starting point instead.
| Unit | Value |
|---|
Duration is the total elapsed time between two specific moments. Unlike age or date difference (which count whole days), duration can include hours, minutes, and seconds for precision — making it the right tool whenever the time-of-day matters as much as the date.
| Tool | Precision | Best for |
|---|---|---|
| Time Duration Calculator (this page) | Days, hours, minutes, seconds | Event timing, flight durations, cooking, sports, medical procedures |
| Day Counter | Whole days only | Deadlines, leave calculations, "days until" questions |
| Age Calculator | Years, months, days | Chronological age from date of birth |
| Mistake | Why it's wrong |
|---|---|
| Rounding to the nearest day too early | Loses precision that matters for anything timed in hours or minutes — a 23-hour 45-minute gap is not "1 day" |
| Ignoring daylight saving transitions | Elapsed time and clock-displayed time can differ by an hour across a DST change |
| Mixing up which date-time is the start vs end | This calculator automatically swaps them if entered in the wrong order, but manual calculations need the correct order for a positive result |
Duration calculations are used in project management, event planning, cooking, sports timing, medical procedures, flight times, and any scenario requiring precise elapsed time measurement.
Beginner:
8 hours.
2 hours.
Advanced:
1 day, 16 hours, 35 minutes.
3 days 6.5 hours = 78.5 hours total.
| Duration | In hours | In minutes | In seconds |
|---|---|---|---|
| 1 day | 24 | 1,440 | 86,400 |
| 1 week | 168 | 10,080 | 604,800 |
| 1 month (30 days) | 720 | 43,200 | 2,592,000 |
| 1 year (365 days) | 8,760 | 525,600 | 31,536,000 |
How do you calculate the duration between two times?
Subtract start from end: duration = end time − start time. If crossing midnight, add 24 hours to the end time. For dates spanning multiple days: convert both to total seconds from a reference point (Unix timestamp) and subtract. The result in seconds can then be converted: divide by 86,400 for days, 3,600 for hours, 60 for minutes.
How do I count the duration of time between two points?
Enter a start and end date or time and this time duration calculator counts the duration between them in days, hours and minutes. It handles durations that span across days and midnight.
What's the difference between duration and date difference?
Date difference (like the Day Counter tool) counts whole calendar days. Duration counts down to the second, which matters whenever the time-of-day is part of the question — flight times, cooking, sports timing, or shift lengths.
Does this calculator account for daylight saving time?
The calculator computes the raw elapsed time between the two date-times you enter. If a daylight saving transition falls between them, the elapsed time and the clock-displayed gap can differ by an hour — enter both date-times as your device displays them and the result reflects actual elapsed time.