Age Calculator
Work out an exact age in years, months and days from a date of birth — plus the total in months, weeks, days and hours, the day of the week you were born on, and how long until the next birthday. Leave the second box empty to measure to today.
Calculate an age
How to use this calculator
- Enter the date of birth.
- Leave the second box empty for the age today, or set a date to get the age on that day — past or future.
- Press Calculate.
How age in years, months and days is counted
Age is counted the way people count it, not by dividing days by 365.25. The whole months between the two dates are taken first, and if the day of the month has gone backwards, one month is dropped and the remaining days counted from there.
That detail matters at month boundaries. From 31 January to 1 March in a common year is 1 month and 1 day: one month after 31 January is 28 February, and then one more day. A naive calculation that borrows "the length of the previous month" gives minus two days, which is how a surprising number of date calculators get this wrong.
If you were born on 29 February
Three years in four have no 29 February, so the next birthday has to fall somewhere. This calculator uses 1 March in a common year and says so in the result. Some jurisdictions use 28 February for legal purposes such as reaching the age of majority; if the date matters legally, check the rule where you are rather than relying on any calculator.
A note on time zones
All the date arithmetic here runs in UTC. That sounds like a technicality and is not: a calculator that builds dates from your local clock can give two people in different countries different answers for the same pair of dates, and can shift by a day across a daylight saving change. Working in UTC throughout means the answer depends only on the two dates you typed.
Frequently Asked Questions
How do I calculate my exact age in years, months and days?
Enter your date of birth and press Calculate. The calculator takes the whole months between the two dates and then the leftover days, which is how people naturally count age, rather than dividing the total days by 365.25.
Can I calculate someone's age on a past or future date?
Yes. Put the date you want to measure to in the second box. Leave it empty and it uses today. This works for both past dates and future ones, so you can answer "how old will I be at the end of next year?".
What happens if I was born on 29 February?
In a year with no 29 February this calculator treats the birthday as 1 March, and tells you it has done so. Some legal systems use 28 February instead, so check the rule where you are if the date has legal weight.
Why does the age in months not match the age in days divided by 30?
Because months are not 30 days. A month can be 28, 29, 30 or 31 days, so the two figures will not agree. The months figure counts real calendar months; the days figure counts real days.
Does my time zone affect the result?
No. All the arithmetic is done in UTC, so the answer depends only on the two dates you enter and not on where you are or on daylight saving.