Duration of Time Calculator

Measure elapsed time, add or subtract durations, compare time zones, exclude weekends, total intervals, and export clear results for planning and records with confidence.

Calculated result
No calculation yet
Duration
Start and end
Calendar and workday settings

Enter ISO dates separated by commas, spaces, or new lines.
Starting date and operation
Projects a recurring interval through repeated cycles.
Duration to apply
Enter a duration
Conversion basis
Months and years require a selected average basis. Calendar months cannot be converted into one fixed number of seconds without an anchor date.
Time intervals
Add separate intervals and calculate their combined duration.
Minutes deducted from every interval.

Recent calculations

No saved calculations yet.

Formula used

Exact elapsed duration: end timestamp − start timestamp
Total days: elapsed milliseconds ÷ 86,400,000
Total hours: elapsed milliseconds ÷ 3,600,000
Business hours: eligible workdays × net hours per workday
Duration conversion: sum of every entered unit expressed in milliseconds

How to use this calculator

  1. Select the required calculation mode.
  2. Enter dates, times, time zones, or duration units.
  3. Choose calendar, rounding, business-day, and display settings.
  4. Press Calculate to view totals and calculation steps.
  5. Copy, print, share, or export the finished result.

Example calculations

ExampleInputExpected result
Same-day duration09:15 to 17:458 hours, 30 minutes
Cross-midnight duration22:00 to next day 06:308 hours, 30 minutes
Add time2 days and 5 hoursStarting date shifted forward
Convert duration90 minutes1.5 hours or 5,400 seconds
Multiple intervals2h 15m plus 1h 45m4 hours

Duration conversion table

UnitEquivalent
1 second1,000 milliseconds
1 minute60 seconds
1 hour60 minutes
1 day24 hours
1 week7 days
1 average month30.436875 days
1 average year365.2425 days

Calendar and business-time notes

Calendar months have different lengths. Leap years also change annual day counts. Exact timestamps remain the safest elapsed-time basis.

Business-day totals use the selected weekdays. Entered holidays are excluded from eligible dates. Break deductions reduce net working hours.

Time-zone differences may cross calendar dates. Daylight-saving transitions can shorten or lengthen elapsed days. The calculator uses browser time-zone rules.

Frequently asked questions

1. Does the calculator support seconds and milliseconds?

Yes. Time inputs support fractional seconds where browsers permit them.

2. Can the end time occur before the start?

Yes. You may keep a signed result, use an absolute result, or reject it.

3. Are months treated as equal lengths?

No. Calendar mode uses date components, while conversion mode uses a selected average.

4. Does it calculate business days?

Yes. Enable business time, select weekdays, and enter excluded holidays.

5. Can different time zones be compared?

Yes. Each elapsed-time endpoint has an independent IANA time zone.

6. Does daylight saving affect results?

Yes. Exact elapsed calculations use the browser time-zone database.

7. Can I add several work sessions?

Yes. The multiple-interval mode totals separate sessions and optional breaks.

8. What does ISO 8601 duration mean?

It is a standardized duration format using letters for date and time units.

9. Can results be rounded?

Yes. Results can be rounded, truncated, or rounded upward by unit.

10. Are recent calculations stored online?

No. Recent entries are stored locally inside the current browser.

11. Can I export results?

Yes. Use copy, CSV, PDF, print, or share-link controls.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.