learn.howToCalculate

learn.whatIsHeading

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.

ステップバイステップガイド

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

解いた例