Why do I sometimes see the gap described as one year different from what I expect?

Whether the year-difference 'looks' the same as the age gap depends on whether both people's birthdays have occurred yet this year — the exact years/months/days breakdown here is always correct regardless.

Can I use this for a pet's age, or something other than people?

Yes — it's pure calendar-date math and works for any two dates.

All tools

Date & Age

Age Difference Calculator

How much older or younger one person is than another, plus each one's current age.

🔒 Runs entirely in your browser — nothing here is ever uploaded

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About the Age Difference Calculator

Calculates the exact age gap between two people in years, months, and days, plus each person's current age.

100% Free Runs in Your Browser No Sign-Up Required

How to use it

Enter both people's birth dates.
Read the age gap and each person's current age in the results.

Formula

Age gap = calendar difference (years, months, days) between the two birth dates, using the same borrow-adjusted method as the Age Calculator

Worked example

Someone born March 15, 1990 and someone born August 22, 1995 have a 5 year, 5 month, 7 day age gap, for as long as both are alive.

Interpreting your result

The age gap itself never changes over time — only each person's individual current age does.

Recommendations

• For just one person's current age, use the Age Calculator directly.
• For a raw day-count between any two dates, use the Date Calculator.

Frequently asked questions

No — it's fixed at the calendar difference between the two birth dates. Only each person's own current age increases.