Age Calculator
Find your exact age in years, months and days, how many days you have lived, and how long until your next birthday.
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Age Calculator by TheCalcTools
How the Age Calculator works
Enter your date of birth and the date you want your age measured at; the second date defaults to today. The calculator subtracts years, months and days, borrowing days from the previous month when needed, which is how people normally count age.
Total days lived is the exact number of calendar days between the two dates. The next birthday is the next calendar occurrence of your birth date, and for people born on 29 February, birthdays in non-leap years are counted on 28 February. Time of day and time zones are ignored.
The formula
Worked example
Born 15 June 1990, measured on 10 October 2026:
| Date of birth | June 15, 1990 |
|---|---|
| Measured on | October 10, 2026 |
- Years: 2026 − 1990 = 36; months: October − June = 4; days: 10 − 15 = −5, so borrow a month: 3 months and 25 days (September has 30 days).
- Exact age = 36 years, 3 months, 25 days.
- Total days lived = 13,266. You were born on a Friday.
Result:
| Exact age | 36 years, 3 months, 25 days |
|---|---|
| Total months | 435 |
| Total days | 13,266 |
| Next birthday in | 248 days (Tuesday, June 15, 2027) |
| Day of the week you were born | Friday |
Frequently asked questions
How is age calculated?
By counting full years since your birthday, then the extra full months, then the remaining days.
Why do two age calculators sometimes give different days?
Month lengths differ. Methods that borrow from the previous month, as here, can differ by a day or two from those that count forward from the birthday.
What happens for a 29 February birthday?
Here, it counts as 28 February in non-leap years. Some countries use 1 March for legal purposes.
Can I count days between any two dates?
Yes, use the date calculator.
Sources and further reading
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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.