Years Between Dates Calculator

Compute years between two dates with a years/months/days breakdown — useful for tenure, anniversaries, and exact-age questions.

Inputs

Result

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How to use this calculator

  • Enter start and end dates.
  • The primary line shows years/months/days. The hint shows the same value as a decimal years count.

About this calculator

When you need an exact "years and months and days" gap — for an age, a tenure, or an anniversary — calendar arithmetic matters. This calculator borrows days from the previous month and months from the previous year the way you would do it on paper, so the breakdown is the one humans expect rather than a raw decimal.

Frequently asked

How does the borrow rule work?+
If the end day-of-month is earlier than the start day-of-month, we have not yet completed the current month — so we borrow one month and add the previous month's day count to the days field. Same idea applied to months and years.
Is this the same as someone's age?+
Conceptually yes — for an age, set start to the date of birth and end to today (or the date you want to know the age on). The age-calculator-detailed tool does exactly this and additionally reports hours/minutes/seconds.
How is February 29 handled when the year is not a leap year?+
A start date of Feb 29 in a leap year is compared against the same day-of-month in the end year. If the end year is not a leap year, Feb 28 is treated as the corresponding day, the same way most calendar libraries handle it.
Why are decimal years and Y/M/D different lengths?+
The decimal uses 365.25 days per year (the average across the Gregorian leap cycle). The Y/M/D breakdown uses calendar-exact arithmetic, which is what you want for anniversaries and ages.
Can I count years backwards?+
Order does not matter — pick any two dates and the result is the absolute difference.

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