Time Duration Calculator

Calculate elapsed hours, minutes, and seconds between local date-time inputs, including overnight shifts.

Measure elapsed time between two local date-and-time entries, with total hours, minutes, seconds, and a days-plus-time breakdown. If both dates match and the end time is earlier, the tool treats it as crossing midnight.

For a span across multiple dates, enter both dates explicitly.

Enter the start date and time.
Enter the end date and time; use a later date for multi-day spans.
Review the elapsed totals and days/hours/minutes/seconds breakdown.
Check the time zone and daylight-saving transition if the interval crosses a clock change.

Elapsed-time method

Elapsed duration = end instant − start instant. For a same-date end time earlier than the start time, the calculator advances the end to the following local calendar day.

Local clock times can be ambiguous or skipped when daylight-saving time begins or ends. This tool uses the browser’s local time zone; it does not ask you to select a time zone or resolve repeated clock times.

How to read the duration

Totals and a split are shown

Total hours, minutes, and seconds are cumulative units. The split expresses complete 24-hour periods and the remaining local-time hours, minutes, and seconds. A daylight-saving transition can make a local calendar day shorter or longer than 24 elapsed hours.

Everyday Life tips and best practices

Use the same local time zone for both entries.
Enter the end date explicitly for a span longer than one overnight.
For work shifts, follow the employer’s timekeeping rules for breaks and clock changes.

Same-day example: 09:00 to 17:00 on the same date is 8 hours, 0 minutes, and 0 seconds.

Overnight example: 22:30 to 06:15 on the same entered date treats the end as the next day: 1 hour 30 minutes to midnight plus 6 hours 15 minutes = 7 hours, 45 minutes, and 0 seconds.

Common mistakes to avoid

Entering an end date that is earlier than the start date.
Assuming every local date has exactly 24 elapsed hours during a daylight-saving change.
Leaving out a date when a multi-day interval is intended.

This is elapsed-time arithmetic, not a payroll, legal-hours, billing, or attendance determination. Time-zone databases and daylight-saving policies can change; verify the relevant clock convention for official records.