# Time duration calculator

> A time duration calculator gives the exact elapsed time between a start and end point — useful for measuring project duration, contract length, or time remaining until an event.

Calculate the exact elapsed time between two dates and times in years, months, days, hours, minutes, and seconds.

**Interactive version:** https://onlinecalculator.me/date-time/time-duration/
**Category:** Date & Time

## Formula

```
Elapsed = End datetime − Start datetime
```

Expressed as: years → months → days → hours → minutes → seconds (remainder after each larger unit is removed).

## Example

From 2026-01-01 09:00 to 2026-01-02 17:30:

```
Duration = 1 day 8 hours 30 minutes
Total hours: 32  |  Total minutes: 1,950
```

## Frequently asked questions

### What if the end time is before the start time?

The calculator returns zero. Check that your dates are in the correct order.

### How are months calculated?

Months are approximated as 30.4375 days (365.25 ÷ 12). For precise month counts, use the date difference calculator.

### Can I measure time down to the second?

Yes. Both the start and end times can include hours and minutes, giving precision to the minute.

### How do I measure a project duration?

Enter the project start date and the actual (or planned) end date. The calculator gives the total elapsed time in all units.

### How do I share my calculation?

Click "Share with my numbers" to copy a URL that saves your start and end times.

## Sources

- [24-hour clock](https://en.wikipedia.org/wiki/24-hour_clock) — Wikipedia
- [Coordinated Universal Time (UTC)](https://en.wikipedia.org/wiki/Coordinated_Universal_Time) — Wikipedia

## Related calculators

- [Date difference calculator](https://onlinecalculator.me/date-time/date-difference/) — Exact days, weeks, and months between two calendar dates.
- [Add or subtract days](https://onlinecalculator.me/date-time/add-subtract-days/) — Find a date a set number of days before or after.
- [Hours calculator](https://onlinecalculator.me/date-time/hours-calculator/) — Add up timesheet hours across multiple shifts.
- [Countdown calculator](https://onlinecalculator.me/date-time/countdown/) — Days, hours, minutes until any future date.

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