Age Calculator
Calculate exact age from a birth date and any as-of date. Instantly see years, months, days, total time lived, and your next birthday countdown.
How to Use
- Enter the date of birth using the date picker.
- Optionally choose a custom as-of date, or leave it set to today.
- Review the exact age shown in years, months, and days.
- Check total months, total weeks, total days, and the next birthday countdown.
Frequently Asked Questions
How does the age calculator work?
It compares the date of birth to the selected as-of date and calculates the precise difference in calendar years, months, and days. It also shows total elapsed time in months, weeks, and days.
Can I calculate age on a past or future date?
Yes. You can change the as-of date to see how old someone was on a past date or how old they will be on an upcoming date.
How is the next birthday countdown calculated?
The calculator finds the next occurrence of the birth month and day after the chosen as-of date, then counts the remaining days until that birthday.
Does the calculator handle leap years?
Yes. Leap years are included automatically. For birthdays on February 29, the next birthday is matched to the last valid day of February in non-leap years.
Why show total months, weeks, and days?
Those totals are useful for forms, milestones, child development tracking, project eligibility checks, or any situation where you need more than just age in years.