Use this calculator for two common time problems: finding the exact duration between two dates and times, or adding and subtracting a span of time from a starting date. Both tools account for days, hours, minutes, and seconds.
Enter a start and end date and time to calculate the exact duration between them.
Start from a specific date and time, then add or subtract a span of days, hours, and minutes to find the resulting date and time.
Calculating elapsed time between two points seems simple, but it gets tricky once dates cross midnight, span multiple days, or need to account for months of different lengths. This tool converts both timestamps into a single point in time, finds the difference in seconds, then converts that back into an easy-to-read breakdown of days, hours, and minutes.
The add/subtract tool works the same way in reverse: it converts your starting date and time into a single timestamp, applies the offset you entered, and converts the result back into a calendar date and clock time — including rolling over into the next or previous day, month, or year automatically.
| Unit | Equivalent |
|---|---|
| 1 day | 24 hours / 1,440 minutes |
| 1 hour | 60 minutes / 3,600 seconds |
| 1 week | 7 days / 168 hours |
| 1 year | 365 days (366 in a leap year) |
Adding or subtracting hours, minutes, seconds, or finding duration between two times.
When units exceed 60, the excess carries into the next larger unit.
Yes, it correctly accounts for day changes when duration spans midnight.