Time

Time Duration Calculator

Free time duration calculator. Find the exact duration between two dates and times, with days, hours, minutes, and total hours or minutes.

YOUR WORKSPACEFree to use. No sign-up.

Start

End

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Enter a start and end time.

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A LITTLE CONTEXT · 3 MIN READTime Duration: From Two Clock Times to Hours and Minutes

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How time duration calculator works

A time duration calculator measures the elapsed time between two moments, accounting for the calendar (including leap years and months of different lengths). It is used for billing, project tracking, event countdowns, and shift planning.

This calculator parses a start and end date-time (YYYY-MM-DDTHH:mm) and computes the difference in milliseconds, then breaks it into days, hours, minutes, and seconds. It also reports the total in hours, minutes, and days as decimals, and produces a compact formatted string like "1d 08:30:00". A reversed range yields a negative total.

Pick a start and end using the date-time pickers and click Calculate. The tool handles cross-day, cross-month, and cross-year spans automatically because it works from the underlying timestamps. Use it for timesheets, countdowns, and any "how long until" question.

Frequently asked questions

What format does the input use?

A date and time in YYYY-MM-DDTHH:mm, picked from the date-time picker. Both the start and end must be supplied.

How are days, hours, and minutes computed?

The difference in milliseconds is divided into whole days (86400s), then the remaining hours, minutes, and seconds. So 32.5 hours shows as 1 day, 8 hours, 30 minutes.

What if the end is before the start?

With full dates and times the totals become negative with a minus sign so you can see the direction. With clock-only times (no date), an end earlier than the start is treated as the next day — 23:00 → 01:00 gives 2 hours, not −22 — and the result is marked as overnight.

Does it account for daylight saving?

It uses the timestamps directly, so a span across a DST change may show an hour more or less than clock time. For billing-sensitive spans across DST, confirm against local clock times.

Time Duration Calculator

Deep dive guides

How time duration calculator works

Frequently asked questions

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