Age calculator
Enter a date of birth to get the exact age in years, months and days, on today's date or any date you choose.
Runs entirely in your browser
Age
- Total months
- 0
- Total weeks
- 0
- Total days
- 0
- Next birthday
- -0 days to go
Born on 29 February: in years without that date, 28 February is used as the birthday.
Dates from year 1 to 9999 in the Gregorian calendar. Ages are counted in whole days; time of birth is not used.
How to calculate an age
- Enter the date of birth.
- Leave Age on as today, or change it to work out an age on another date, such as an application deadline.
- Read the age in years, months and days, the totals, and how long until the next birthday.
How an exact age is counted
Years and months are counted the way people count birthdays: you are a year older on the same day and month as your birth, and a month older on the same day of each month. When that day doesn't exist (31 April, or 29 February in a common year), the last day of the month is used instead. Whatever is left after the last whole month is the days.
The totals are simpler. Total days is the number of calendar days from the birth date to the Age on date, total weeks is that divided by seven and rounded down, and total months is the years times twelve plus the months.
The calculation uses calendar dates only, never clock time, so a daylight saving change or a time zone difference cannot shift the answer by a day. The one thing that depends on your device is which date counts as today.
Tips
- Need the gap between any two dates, or business days? Use the date difference calculator.
- Working out what share of a lifetime something took? The percentage calculator shows the formula.
Questions
How is the age in years, months and days worked out?
The calculator counts whole months forward from the birth date for as long as it doesn't pass the target date, then counts the days left over. Someone born on 31 January 1990 is 34 years, 1 month and 1 day old on 1 March 2024: 34 years and 1 month takes the count to 29 February 2024 (the last day of February), and one more day reaches 1 March.
What about people born on 29 February?
In years without a 29 February, this calculator treats 28 February as the birthday, so someone born on 29 February 2000 turns 23 on 28 February 2023. Laws differ on this: some places treat 1 March as the legal birthday in common years, so for official purposes such as licences or benefits, check the local rule.
Does the time zone matter?
Only for what counts as today. The default Age on date is today's date on your device. All the arithmetic is done on calendar dates, so daylight saving changes never add or lose a day.
Why might another site show a different number of months or days?
Months have different lengths, so there is more than one reasonable way to split an age into months and days, especially near the end of a month. The totals in days and weeks are the same everywhere; the years, months and days split here follows the rule described above.
Can I use it for something other than a person?
Yes. It works for anything with a start date: how old a company, a building or a pet is, or how long ago an event happened. For two arbitrary dates, with business days and an option to include the end date, the date difference calculator is a better fit.