Dates & Time

Years Between Dates Calculator (Exact Span)

Pick two dates and it returns the gap in years, months, and days, plus decimal years and the totals in months, weeks, and days. Use a birth date as the first date and it doubles as an age calculator.

How to use
  1. Enter the start date and the end date.
  2. For an age, put the date of birth first and leave the end date as today.
Span back
Years, months, days
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Decimal years
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Total months
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Total weeks
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Total days
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Date math uses your inputs as given; check time-zone and leap-year edge cases.
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How it's calculated

Δ = End − Start → years, months, days; decimal years = total days ÷ 365.2425

Start, End = the two dates, Δ = elapsed time. Months and days borrow from actual calendar month lengths. Total days = exact day count. Age mode also finds the next birthday.

Common questions

Does it count leap years?

Yes. The day-level math uses the real calendar, so February 29s are included in the totals.

What are decimal years?

It's the span written as a single number, like 7.42 years, which is handy for spreadsheets and interest math.

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