Two birthdays · Two ages · Two dates
Age Difference Calculator
Measure time between two lives
This free age difference calculator — also known as an age gap calculator or an age calculator between two dates, and sometimes searched as an age calculator difference — works out the exact gap between two birthdays or two ages in years, months and days, and tells you who is older.
The Calculator
Result
Your result will appear here — enter two birth dates or two ages, then press Calculate.
How the calculation works
Enter two birthdays and the calculator finds who was born earlier, counts the full years between the dates, then the remaining months and days. Leap years, February 29 and month lengths are handled automatically, so you never see a negative month or day. If you only know two current ages, switch to the ages mode for a whole-year difference. Our guide to age difference by birthday and age explains what each input mode gives you.
The result also shows the total number of days between the two birth dates and whether the two people share the same birthday. Everything runs in your browser — nothing is sent to a server.
What you can do next
- Dating age calculator
Enter an age and get the half-your-age-plus-7 range: the minimum and maximum partner ages the popular rule suggests.
- Half your age plus 7, explained
A neutral explainer of the dating age rule: the formula, where it came from, and what critics say.
- Is a 3, 7 or 10 year age gap big?
A reference table for common year gaps between adults, with the context in which each is usually discussed.
- How to calculate age difference by hand
The age difference formula step by step, with borrowing for months and days and a worked example.
Age difference questions
What is an age gap?
An age gap is the difference in age between two people, usually partners. It can be stated in years alone, or more precisely in years, months and days. You can compute the exact figure from two birthdays with our age difference calculator, then read neutral context about how different gaps are commonly discussed.
What is the age difference between two people?
The age difference is how much older one person is than the other. Subtract the younger person’s birth date from the older person’s, then refine with months and days. Two people born on the same date have a difference of zero. Our calculator gives the exact figure from two birthdays or two ages.
How is age difference calculated?
Take both birth dates, find who was born earlier, then count the full years, remaining months and remaining days between the two dates. Leap years and month lengths are handled by borrowing, so the result never shows negative months or days. The step-by-step guide explains the hand method.