Best for exact calendar age
Use Age Calculator to find age in completed years, months, and days from a birth date or start date.
About Age Calculator
It turns out that dividing days by 365.25 doesn't give you an exact age - leap years and varying month lengths mean the years/months/days breakdown has to use real calendar arithmetic. This calculator does it right: complete years, then complete remaining months, then remaining days, the same way official documents calculate age. Useful for filling in forms that ask for precise age, checking eligibility cutoffs, tracking a baby's age in months, or planning milestone birthdays. The reference date defaults to today but you can change it to any date - handy for calculating age at a specific point in time. Everything runs in your browser; no date is stored anywhere.
Age Calculator details
Calendar arithmetic
The calculator uses real calendar dates, so leap years and different month lengths are handled correctly.
Custom reference date
The reference date defaults to today, but you can change it to calculate age on a past or future date.
Extra results
The tool also shows total days lived, weeks, and the countdown to the next birthday when relevant.
Client-side privacy
Date calculations run in your browser. Birth dates and reference dates are not uploaded to the server.
Common age-calculation differences
Approximate methods that divide by 365 or 365.25 can differ from official age because official age is based on completed calendar years, months, and days.
How it works
1
Enter the date of birth
Pick the birth date from the date picker - and optionally set a custom reference date instead of today.
2
See the exact age
Years, months, and days are calculated using real calendar arithmetic.
3
Check the extras
Total days lived, weeks, and the countdown to the next birthday are shown below.
Frequently asked questions
How is age calculated exactly?
With calendar arithmetic: complete years first, then complete months, then the remaining days - correctly handling leap years and months of different lengths.
Can I calculate age at a past or future date?
Yes - change the reference date to any day, for example to find someone's age at graduation or on a contract start date.
Why does my result differ from other calculators?
Tools that divide by 365.25 give approximate results. This calculator uses the same method as official documents: completed years, then months, then days.
Is my birth date stored anywhere?
No - the calculation runs in your browser and the date is never sent anywhere.