Age Calculator
Enter a date of birth to get an exact age in years, months and days, along with the total days lived and a countdown to the next birthday.
Why the day count isn't just subtraction
Simply subtracting years doesn't account for whether the birthday has already happened this year, and months have different lengths — so this tool borrows from the previous month when the "as of" day of the month falls before the birth day, the same way you'd borrow when subtracting by hand.
Common uses
- Checking exact eligibility ages for school enrolment, pensions, or age-restricted services
- Working out the precise gap between two people's ages
- Counting down to a birthday or anniversary
- Calculating tenure or duration between any two dates, not just birthdays
Frequently asked questions
How do I calculate my exact age in years, months and days?
Enter your date of birth and leave the "as of" date blank to use today — the calculator subtracts year, month and day components (borrowing across months the way you would in long subtraction) to give your exact age.
Can I calculate someone's age on a specific past or future date?
Yes — fill in the "as of" date field with any date instead of leaving it on today's date, and the calculator will show the exact age (or time elapsed between two dates) as of that day.
How many days old am I?
The result panel shows total days lived alongside the years/months/days breakdown, calculated as the exact number of days between your date of birth and the reference date.
Does this account for leap years?
Yes — the calculation uses JavaScript's native date arithmetic, which correctly accounts for leap years and varying month lengths automatically.