Time Duration Calculator

Calculate the exact duration between two date-time values. Results include years, months, weeks, days, hours, minutes, seconds, ISO duration, and total seconds.

How This Calculator Works

This tool uses calendar-aware logic to compute the exact duration between two date-time inputs. It accounts for different month lengths, leap years, and timezone behavior handled by your device.

Formula / Method

The engine follows a two-step calculation:

  • Add whole years until the next addition would exceed the end date.
  • Add whole months until the next addition would exceed the end date.
  • Compute the remaining difference using seconds, then convert to weeks, days, hours, minutes and seconds.

Example

Start: 2024-01-31 10:00
End: 2025-03-05 15:30

Result: 1 year 1 month 5 days 5 hours 30 minutes.

Input Rules

  • Both Start and End must be valid date-time values.
  • All date-times use your device's local timezone.
  • Negative durations are allowed (if End is earlier than Start).

Frequently Asked Questions

Yes, leap years automatically affect month lengths and calculations.
DST changes are handled by your browser's timezone rules.
Yes—set the birth date as Start and today’s date as End.
Human-readable uses calendar units; total seconds is a raw timespan.