Age Calculator
Age in years, months and days, and the next birthday. Free, and runs entirely in your browser — nothing you enter is uploaded, stored or sent to a server.
About Age Calculator
How old someone is on a given day, counted the way a calendar counts rather than by dividing days by 365.25. That distinction matters at the edges: a birthday that has not happened yet this year, a 29 February, the difference between three months and ninety days.
Alongside the years, months and days it gives the same span in months, weeks, days and hours — the numbers people actually want for a form, a visa application or a milestone — plus the weekday you were born on and how far away the next birthday is.
Leave the second date empty for today. Fill it in to answer the other question this tool is for: how old will someone be on a date in the future, or how old were they on one in the past.
Where it helps
- Counts on the calendar, so months of different lengths and leap years both come out right.
- Gives the age in months, weeks, days and hours as well as in years.
- Answers the future question too: how old someone will be on a given date.
- Says which weekday you were born on, which is the detail everyone actually wants.
- Runs locally — a date of birth is personal data and it stays in the browser.
Limits
- Whole days only: it ignores the time of day and the time zone you were born in.
- Some legal systems compute an age differently at the margins, particularly around 29 February.
- It is a calendar calculation, not an official document.
Frequently asked questions
How is someone born on 29 February aged?
Their birthday falls on 1 March in a common year here, which is the usual convention. The years count normally: the leap day only affects which day the birthday lands on.
Why does the day count differ from years times 365?
Because leap years exist. Ten years is 3,652 or 3,653 days depending on how many of them fell inside the span, and this counts the real ones.
Can I work out an age on a future date?
Yes — put the future date in the second field. That is how to answer "will they be 18 by the time term starts".
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