Age Calculator
Work out exact age in years, months and days from a date of birth, plus totals in months, weeks, days and hours, and a countdown to the next birthday. Calculates in your browser.
Age
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How age is counted
Age is the completed years since birth, then the leftover whole months and days, the everyday way of saying it. Each month uses its real length, so a birthday on the 31st still ages correctly through shorter months.
The “age at date” defaults to today but you can set it to any date, handy for working out how old someone will be at a future event, or was at a past one. Everything is computed locally in your browser.
What this does
An age calculator works out an exact age from a date of birth (in years, months, and days) plus totals in months, weeks, days, and hours, and a countdown to the next birthday.
How to use it
- Enter a date of birth.
- Leave “age at date” as today, or set another date.
- Read the years/months/days age and totals.
- See the days until the next birthday.
How it works
It counts completed years since birth, then the leftover whole months and days, using each month’s real length, the same way you would say someone’s age out loud.
age = date − date of birth
Understanding your result
Age is shown the way people say it aloud: completed years first, then the leftover months and days, so it only ticks over on the birthday rather than rounding up. Use the totals in months or days for milestones and the next-birthday countdown for planning, but for a legal or medical cut-off confirm the exact date the rule actually uses.
Example
Someone born on 1 January 2000 is 26 years old on 1 January 2026.
Sources & methodology
Last updated .
Frequently asked questions
How is age calculated?
It counts completed years since birth, then the leftover whole months and days, using each month’s real length, the same way you would say someone’s age out loud.
Can I find age at a future or past date?
Yes. Change the “age at date” field from today to any date to see how old someone will be, or was, on that day.
Is my data stored?
No. Everything is calculated locally in your browser.
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