How are leap years handled?

Correctly, including the century rule: 2000 was a leap year, 1900 and 2100 were not. Because the calculation walks the calendar rather than dividing by 365.25, a born-on-February-29 date gives an exact age.

When is someone born on 29 February legally an year older?

It depends on jurisdiction — some count March 1, some February 28. This tool celebrates on February 28 in a non-leap year; check the rule that applies before relying on it for anything contractual.

Can I find an age at a past date?

Yes — set the optional 'age at' date to any day on or after the birth date. That is how you answer 'was they 18 on the contract date' without mental arithmetic.

Is the total-hours figure accurate?

It multiplies whole calendar days by 24, so it ignores leap seconds and assumes uniform days. Fine for a sense of scale, not for billing.

Calculators & Converters Ready to use

Age Calculator

Get an exact age in years, months and days from a date of birth, or the age at any past or future date, with totals in months, weeks, days and hours.

Date of birth

Age at date (optional)

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This tool runs entirely in your browser. Your input never leaves your device.

About Age Calculator

'How old are you' is a calendar question, not a division. Subtracting days and dividing by 365.25 gives an answer that is wrong at the edges, because months are not equal and leap years are not every four years — they are, except for century years that do not divide by 400. This calculator walks the calendar instead: years to the last birthday, months on that date, days remaining, so a result of '36 years, 4 months, 11 days' is exact rather than approximate.

Enter a date of birth and it uses today; add an 'age at' date and you get the age on any past or future day, which is what a form needs when it is checking an eligibility cut-off, a pension date, or a deadline that lands between birthdays. Alongside the precise age: total months, weeks and days, an hours-and-minutes figure (whole days, so treat it as indicative), the day of the week the person was born on, and the next birthday with how many days away it is.

February 29 birthdays are handled the way most registries do: celebrated on February 28 in a non-leap year. Everything is computed on the page — no submission, and no storage of a date that identifies someone.