Age calculator
Exact age in years, months and days
Enter a date of birth. Change the second date to find an age on any past or future day.
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Born on 29 February: in years without a leap day this page counts the birthday as 1 March. Some places use 28 February instead.
- Next birthday
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- Day of the week born
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- In months
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- In weeks
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- In days
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- In hours (whole days x 24)
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How the age is worked out
The calculator counts completed years, then completed months since the last birthday, then the days left over. A year is complete on the birthday itself, not the day before. A month is complete when the day number of the birth date comes round again. When a month is too short to have that day, for example someone born on the 31st in a month with 30 days, the month completes on the 1st of the next month.
Age on another date
The second box starts as today. Change it to find an age on a past or future date, such as a school cut-off, an application form that asks for age "as of" a set day, or how old someone was at an event.
Born on 29 February
In years without a leap day this page treats the birthday as 1 March. So a person born on 29 Feb 2024 is still 0 on 28 Feb 2025, turns 1 on 1 Mar 2025 and turns 4 on 29 Feb 2028. That is a common convention, but it is not universal: New Zealand, for one, uses 28 February for legal purposes. Check the local rule if the exact day has legal weight.
The other figures
Months, weeks, days and hours are the same span measured in a single unit. The next-birthday figure counts whole days from the "age on" date. Everything uses the modern (Gregorian) calendar and whole dates. Time of birth and time zones are ignored, so a person born late in the evening is treated as born on that calendar date.