How to Calculate Date Difference

What is Date Difference?

A date difference calculator finds the number of days, weeks, months, or years between two dates. Used to calculate ages, contract durations, time between events, and project timelines.

Step-by-Step Guide

1. 1Count calendar days: convert both dates to a day number from a fixed epoch, subtract
2. 2For years/months: count complete years and months, then remaining days
3. 3Leap years must be accounted for (Feb 29 only exists in leap years)
4. 4Business days: subtract weekends and optionally public holidays

Worked Examples