Age calculator
Enter a birth date to get exact age in years, months, and days — including on a date you choose.
How to calculate exact age
1. Enter the date of birth in YYYY-MM-DD format.
2. Optionally change the “as of” date (today is the default).
3. Read the result in years, months, and days.
4. Adjust the date if you want age on another day in the past or future.
Examples
Child’s age for a form
A child born 2018-03-12, calculated on 2026-08-11. The result shows full years plus months and days — handy for preschool or sports registration.
Age on a specific day
You want to know how old someone was on a wedding day or exam date. Set the birth date and the event date.
Checking adulthood
Quickly see whether someone has turned 18 on a given day — especially when the birth day and month do not match the reference date.
When to use it
• For forms that require an exact age.
• When planning birthdays, anniversaries, and events.
• When you need age on a day other than today.
How we count full years, months, and days
We start with the calendar year difference, then adjust months and days. If the target day falls earlier in the month than the birthday, we borrow days from the previous month. This matches the “completed” years and months that school and sports forms usually expect.
Frequently asked questions
How exactly is age calculated?
We subtract full years, then months, then remaining days, accounting for different month lengths and leap years.
What date format is required?
YYYY-MM-DD, e.g. 2015-06-15. This format is unambiguous in any language.
Can I calculate age on a specific day?
Yes — set the target date instead of today.
What if the target date is before the birth date?
We show an error message about the date order.
Is the birth date stored?
No. Dates stay only in browser memory for your session on the page.