User manual
Time Duration Calculator User Manual
Use Time Duration Calculator for one elapsed interval between a Start date/time and an End date/time. The result uses deterministic Gregorian civil-time arithmetic rather than your device timezone.
Quick start
- Enter Start date.
- Enter Start time.
- Enter End date.
- Enter End time.
- Read the Duration and exact totals.
- Use Copy result if you want a plain-text summary.
Date and time input
Dates use the unambiguous YYYY-MM-DD value model. Times use 24-hour HH:MM or HH:MM:SS. If seconds are omitted, the engine treats them as 00.
Valid Gregorian dates
The engine validates month length and the Gregorian leap-year rule. For example, 2000-02-29 is valid, while 1900-02-29 and 2100-02-29 are not.
Equal and reversed endpoints
Equal Start and End timestamps produce exact zero. If End is earlier than Start, the app rejects the interval rather than guessing, swapping, or taking an absolute value.
Reading the result
Duration is decomposed into fixed 24-hour days, hours, minutes, and seconds. Total days, hours, and minutes are ratios rounded half-up to at most six decimal places. Total seconds is exact.
Timezone and DST boundary
This app has no timezone input. Each civil day is exactly 24 hours. If you need the actual elapsed time across a daylight-saving or timezone change, use a timezone-aware product instead.
Privacy and saving
Entered values stay in page memory. Refreshing or closing may discard them. The app does not create a saved calculation history.