Age Calculator
Enter a date of birth to calculate exact age in years, months, and days — plus a countdown to the next birthday.
Also covers: chronological age calculator, age calculator by date of birth, age calculator on date, age calculator on today
Age Calculator
Related picks
Affiliate disclosure: these are demo Amazon links — we may earn a commission on qualifying purchases once you add your own Associates tag.
Calendar Wall Clock
Date, day, and time in one glance — no phone required.
Useful for tracking deadlines calculated with the tools on this page.
View on AmazonDesk Planner & Calendar Pad
A physical planner for logging dates and countdowns.
Pairs a written record with the date math you calculate here.
View on AmazonHow the Age Calculator works
- Enter the date of birth.
- Optionally set a different 'as of' date instead of today.
- Read the age in years, months, and days, plus total days lived and days until the next birthday.
Formula / logic
Age = (Reference date − Date of birth), broken into full years, then full months, then remaining days.
Worked example
Born June 15, 1990, measured on September 6, 2026: 36 years, 2 months, 22 days old.
Frequently asked questions
Can I calculate age as of a specific date rather than today?
Yes — set the 'as of' date to any point in the past or future to see age on that day, useful for eligibility or legal age checks.
How is age in months and days calculated?
The tool counts full years first, then the remaining full months, then the leftover days — the same way age is conventionally described.
Can I calculate someone's age on a future or past date?
Yes — set the 'as of' field to any date to check age eligibility for a program, contract, or legal requirement on that specific day.
How is a leap-year birthday (Feb 29) handled?
In non-leap years, an age calculation for a February 29 birth date typically resolves against February 28 or March 1 depending on convention; this tool uses the standard calendar rollover.
Is the Age Calculator free to use?
Yes — every calculator on this site is free, with no sign-up or download required.