Enter a date of birth to get the exact age in years, months and days — plus total months, weeks and days.
How this calculator arrives at its answer
This age calculator finds the precise time between a birth date and any date you choose (today by default). It returns years, months and days, and also the totals in months, weeks and days.
It’s handy for birthdays, forms, eligibility checks and working out age gaps.
How to use it
- Enter the date of birth.
- Optionally change the “age at” date (defaults to today).
- Read the exact age and the totals.
The formula
age = calendar difference between the two dates,
carrying days into months and months into years
Try it with these numbers
On the values this calculator opens with, the age is 26 y 7 m 10 d. Underneath, Months comes out at 319 and Weeks at 1,388. Change any field and every figure updates as you type.
Frequently asked questions
How do you calculate exact age?
Take the year, month and day difference between the two dates, borrowing from the next unit up when a value goes negative — exactly how the calculator does it.
Can I find age on a future or past date?
Yes — change the “age at” date to any date to see the age then.
Does it handle leap years?
Yes — it uses real calendar dates, so leap days are counted correctly.