Worked example
Age calculation example
For a date of birth of 14 May 1990 and an age-as-of date of 21 August 2025, the result is:
35 years, 3 months and 7 days
That is 423 completed months and 12,883 total days.
Free date of birth tool
Your exact age, made clear.
Calculate your age in years, months and days from your date of birth, then see total days, weeks, months and your next birthday.
Calculator
Find your exact age
Your result will appear here
Add the dates to get started.
Enter your date of birth to see your exact age, totals and next birthday.
The basics
How age is calculated
Age is the calendar time between a date of birth and a chosen age-as-of date. The calculator counts complete calendar years first, then complete months, then the remaining days.
It uses real month lengths and leap years rather than dividing the number of days by an average year. That keeps results meaningful around birthdays, February and the end of a month.
The result is calculated locally in your browser. Your dates are not sent anywhere or stored by this tool.
Calendar precision
Age in years, months and days
A result such as 35 years, 3 months and 7 days means 35 complete birthdays have passed, followed by three complete calendar months and seven additional days.
Because months have different lengths, this exact format is more useful than converting every age into an average number of months or years.
Next birthday
How many days until my next birthday?
The calculator finds the birthday in the current calendar year. If it has already passed, it moves to the next year and counts the calendar days from your selected age-as-of date.
For birthdays on 29 February, the displayed birthday is 28 February in a non-leap year and 29 February in a leap year.
Optional mode
Age difference between two dates
Use the Age difference tab in the calculator to compare two birthdays, an anniversary and today, or any other pair of dates. It accepts the dates in either order and reports the absolute difference in years, months, days, total months, weeks and days.
Questions, answered
Age calculator FAQs
How does the age calculator work?
Enter your date of birth and an age-as-of date. The calculator works through completed calendar years, months and days, while also showing total completed months, weeks and days.
How many days until my next birthday?
The calculator compares your next birthday with the age-as-of date. If your birthday is today, the result is zero; otherwise it shows the number of calendar days remaining.
How is a February 29 birthday handled?
A February 29 birthday is shown as February 28 in a non-leap year. In a leap year, the birthday remains February 29, and the calendar calculation accounts for the extra day.
Can I calculate the age difference between two dates?
Yes. Choose Age difference, enter two dates in either order, and the calculator will show the absolute difference in years, months, days, total months, weeks and days.
Does the calculator store my date of birth?
No. All calculations happen in your browser. The page does not send the dates to a server, use a database or require an account.