Age Calculator

What this age calculator does

Give it a birth date and it works out exactly how old someone is — not just the year count, but the precise years, months and days that have passed. It also totals up how many days, weeks and months you have been alive and tells you how many days remain until your next birthday. Everything runs on your own device, so no dates are ever uploaded or stored.

How age in months and days is worked out

Simple subtraction of years is easy to get wrong, because months have different lengths and leap years add a day. This tool counts up from your birth date: it subtracts the day, month and year, then "borrows" days from the previous calendar month whenever the day-of-month hasn't been reached yet. That matches how people naturally say their age — for example, "34 years, 2 months and 11 days" — and stays accurate across leap years and month boundaries.

How to use it

1. Click the Date of birth field and pick or type the birth date.
2. Leave As of date on today, or change it to calculate age at a past or future date.
3. Press Calculate age (it also updates the moment you change a date).
4. Read the exact age, total days, weeks, months, and the countdown to the next birthday.
5. Use Reset to clear the birth date and start again.

FAQ

Can I find my age on a specific past or future date?

Yes. Change the "As of date" to any date on or after the birth date, and the age is calculated as of that day instead of today.

How are leap years handled?

The math uses real calendar month lengths, so February 29 and leap days are counted correctly. A Feb 29 birthday in a non-leap year rolls to March 1 for the next-birthday countdown.

Is my birth date sent anywhere?

No. All calculations happen in your browser. Nothing is uploaded, saved, or shared.

Why does the next-birthday count say a large number?

It counts full days from the "as of" date to the upcoming birthday. On the birthday itself it shows "Today!" instead of a number.