Free time duration calculator
Enter a start and end time — this time duration calculator returns the exact duration in hours, minutes, and seconds, updated live, as you type.
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Date calculations use calendar days. Working days exclude weekends but not public holidays unless noted.
Results are estimates. Consult a professional.
How the time duration calculator works
Enter a start time and an end time — with seconds if you need them — and the calculator returns the elapsed duration in h:mm:ss format. This is the same arithmetic as the hours calculator, but displayed with full seconds precision rather than decimal hours. For events spanning more than one day, enter the number of additional days and the calculator adds 24 hours per extra day.
Worked example: meeting from 9:15 AM to 11:40 AM
A team meeting starts at 9:15:00 AM and ends at 11:40:30 AM. The organiser wants the exact duration in h:mm:ss to log it in a time-tracking system.
Common event durations for reference
Use these typical durations as a sanity check when timing events or planning schedules.
| Event | Typical duration |
|---|---|
| Team meeting | 1:00:00 |
| Lunch break | 0:30:00 – 0:45:00 |
| Flight New York → Los Angeles | 5:20:00 |
| Marathon (average finisher) | 4:00:00 – 4:30:00 |
| Standard workday | 8:00:00 |
| Recommended sleep | 7:00:00 – 9:00:00 |
Source: ISO 8601 duration conventions; flight and race times are typical averages. Individual results vary.
Tips for measuring time duration
h:mm:ss format is the most readable for events, while decimal hours are better for calculations. Knowing when to use each saves time when logging or billing.
- Use h:mm:ss for event logs and sports — it matches stopwatch readouts and is immediately readable without conversion. A race time of 1:23:45 is clearer than 1.396 hours.
- Convert to decimal for billing — if your rate is charged per hour, multiply the decimal-hours figure by your rate. Avoid multiplying h:mm:ss directly by a rate — it produces a wrong result.
- For multi-day durations, add the days field — a 26-hour event is not the same as a 2-hour event. Enter 1 extra day and the end time to get 26:00:00.
- Track cook times and bake times — enter the start time when food goes in the oven and the end time when the timer rings to confirm the actual elapsed time matches the recipe.
- Travel planning — enter your departure and arrival times to get door-to-door duration, then compare flights or route options side by side.
Accuracy and limitations
The time duration calculator is accurate to the second for any duration up to 99 hours and 59 minutes when a day-count field is used. It follows standard clock arithmetic — borrowing seconds from minutes and minutes from hours — so the result is exact for any valid time input.
The calculator does not account for time zone differences between start and end locations, daylight-saving-time transitions within the duration, or calendar date changes beyond a simple day count. If your start and end are in different time zones, convert both to the same zone (UTC is easiest) before entering them.
Time duration terms defined
About this time duration calculator
This calculator runs entirely in your browser — nothing you enter is sent to any server.
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