Find your exact age in years, months, and days from your date of birth, count the days between any two dates, and see how long until your next birthday.
Your age
Enter your date of birth
Days until next birthday
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Difference
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How It Works
Your age in years is calculated from the difference between today and your date of birth. The result is broken into whole years, then remaining months, then remaining days, so it always matches the way people normally describe their age rather than a single decimal.
For the days-between-two-dates mode, the calculator counts the total number of days on the calendar from the start date to the end date, inclusive of the end date.
Days until your next birthday is the number of days from today to the next annual occurrence of your birth month and day. If your birthday already passed this year, it rolls forward to next year.
Worked example: someone born on March 15, 1990 checking on October 19, 2026 is 36 years, 7 months, and 4 days old — about 13,372 days, or 36.61 years. Their next birthday is about 147 days away.
Frequently Asked Questions
Does the age calculator account for leap years?
Yes. It uses the real calendar, so leap years and months with different numbers of days are handled automatically when computing years, months, and days.
What is the difference between age in years and exact age?
Age in years is a single rounded number. Exact age breaks the time into years, plus remaining months, plus remaining days, which is more precise and matches how age is normally stated.
Can I use this to count days until an event?
Yes. Use the days-between-dates mode with today as the start date and your event as the end date to get the number of days until it arrives.
How is exact age in years, months, and days computed?
The calculator subtracts the birth year, month, and day from today separately, borrowing from the next larger unit when a subtraction goes negative — the same way you subtract by hand. This keeps the months and days aligned to the calendar rather than converting everything to a single decimal.
Does the calculator count the end date in the days-between mode?
Yes, the end date is included. If you need to exclude it, subtract one from the result. For a start of Jan 1 and an end of Jan 10, the tool reports 9 days between them.
Why does "days until next birthday" sometimes show 365 or 366?
If your birthday was yesterday, the next occurrence is almost a full year away. In a leap year that can be 366 days, and in a common year 365 — the calculator uses the real calendar to account for February 29.