⚖️ Age Difference Calculator
Comparing your age with a sibling, partner, friend, or colleague? Enter both dates of birth and this tool works out exactly who's older, and the precise gap in years, months, and days — plus the total number of days and weeks between the two birth dates.
How the Age Difference Calculator works
The calculator identifies the earlier birth date automatically, then computes the calendar difference to the later one using the same exact year/month/day arithmetic as the main Age Calculator — no rounding, no approximations.
Step-by-step calculation
- 1Enter the first person's birth date.
- 2Enter the second person's birth date.
- 3The earlier date is found automatically.
- 4The calendar gap is counted in years, months and days.
Worked example
Someone born June 1, 1985 is 4 years, 3 months and 10 days older than someone born September 11, 1989.
Age Difference Calculator examples
| Second person born | Result |
|---|---|
| Dec 25, 1985 | 0 years, 6 months, 24 days apart |
| Mar 10, 1988 | 2 years, 9 months, 9 days apart |
| Sep 15, 1990 | 5 years, 3 months, 14 days apart |
| Jan 1, 1995 | 9 years, 7 months, 0 days apart |
| Jun 1, 2000 | 15 years, 0 months, 0 days apart |
First person born June 1, 1985. Other inputs kept at the calculator's default values. Results calculated by this calculator.
Why use an Age Difference Calculator?
Compare ages between siblings, partners, friends or coworkers quickly and exactly.
Important factors that can affect your results
- Leap days between the two dates.
- Month lengths (28–31 days) when counting the months.
- Entering the dates in the wrong format.
Frequently asked questions
Does it matter which date I enter first?
No — the calculator automatically figures out which person is older regardless of the order you enter the two dates.
Can I use this for age-gap questions in relationships?
Yes, it works for any two people's birth dates — the math is the same regardless of the relationship.
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Last reviewed November 2026 · How we build and check our tools · Report a problem