About this tool
Your age in whole years is easy. Your exact age, such as 24 years, 3 months and 12 days, needs care because months have different lengths. This calculator uses calendar arithmetic rather than dividing days by 365.
Enter a date of birth and the tool shows exact age, the date and countdown to your next birthday, total days lived and the weekday you were born. You can also set a different "age at" date to find someone's age on a past or future day.
How to use the Age and Next Birthday Calculator
- Pick your date of birth with the date field.
- Leave "Age at date" as today, or change it to see age on another date.
- Press Calculate.
- Read your age, countdown to the next birthday and the extra facts underneath.
Practical examples
How it works
Years, months and days are found by subtracting the date parts and borrowing from the previous month when the day count goes negative, using the real length of that month (including 29 days for February in leap years).
Days until the next birthday = (next birthday date - today) in whole days, calculated on UTC dates so daylight-saving changes never shift the result. If the birthday is today, the count is zero.
Future dates of birth are rejected with an error message.
Privacy and file processing
Your date of birth is used only in your browser to do the calculation.
See our Privacy Policy for details on cookies, local storage and advertising.
Frequently asked questions
How are leap-day birthdays handled?
In years without 29 February the birthday is shown as 1 March. Some people celebrate on 28 February; the choice is cultural and legal conventions vary.
Why does my age in days differ from years x 365?
Leap years add an extra day roughly every four years.
Can I calculate someone else's age on a specific date?
Yes, set "Age at date" to that date.
Is my birth date stored?
No. It is used for the calculation in your browser only.
Related tools
Results are for general information. Check important figures against official sources. Read the disclaimer.