Age Difference Calculator
Two birthdays. One clear answer. See who is older and find the age gap in complete years, months and days—instantly.
Compare two birthdays
Results appear automatically as soon as both dates are entered.
Choose two valid dates of birth above. No Calculate button needed.
The result uses complete calendar dates, not birth times. For February 29 anniversaries in non-leap years, the calculation follows the February 28 convention; legal age rules can vary.
How does the age difference calculator work?
It compares two dates of birth. The earlier birth date belongs to the older person. The result measures the calendar interval between the dates, not just the difference between birth years.
Choose the date of birth of Person 1. Adding a name is optional.
Choose Person 2’s date. The result updates automatically.
View the gap in calendar years, months and days, plus total days and weeks.
Why full dates matter
Comparing years alone can be misleading. For example, someone born on December 31, 2024 and someone born on January 1, 2025 are only one day apart, even though their birth years differ.
Leap years and variable month lengths matter as well. The year-month-day breakdown follows calendar anniversaries; total days counts the actual midnights between the two birth dates.
Frequently asked questions
How do you calculate the age difference between two people?
Enter both birth dates. The earlier birth date belongs to the older person. The calculator measures the calendar difference from that date to the later birth date in complete years, remaining months and days.
Does the calculator account for leap years?
Yes. It uses actual calendar dates, including February 29 in leap years, rather than assuming every year has 365 days or every month has 30 days.
What if both people were born on the same day?
If both birth dates are identical, the age difference is zero days. This date-only tool cannot compare birth times within the same day.
Is the age difference based on today's date?
No. The age gap between two known birth dates stays the same. You do not need to enter today's date to compare them.
Are my names or birth dates stored?
No. This calculator runs in your browser and does not send the entered names or dates to our server. The optional copy feature copies only when you click it.