Age Calculator
Work out an exact age in years, months and days, plus total days lived and the countdown to the next birthday.
Enter a date of birth to see the exact age.
How to use this tool
- Enter the date of birth in the first field, including a four digit year.
- Leave the second field on today's date, or change it to work out an age on any other day (a passport deadline, a school cut off, a policy renewal).
- Read the answer straight away. It updates as you change either date, so there is nothing to submit.
- Check the cards underneath for total days, weeks, months and hours, the weekday of birth, and how long until the next birthday.
About this tool
This age calculator turns two dates into an exact age: full years first, then the leftover months, then the leftover days. That is the order official forms ask for, which is why "36 years, 7 months and 20 days" is more useful than a rounded decimal. Getting it right is fiddlier than it looks. February changes length every fourth year, months run from 28 to 31 days, and when a birthday has not come round yet in the current month the borrowed days have to come from the correct previous month. This tool borrows from the real calendar rather than assuming a 30 day month, so the answer is exact for every date you can enter. Two things it deliberately does not do. It does not read your dates in UTC, because a date of birth is a calendar date rather than a moment in time, and reading it in UTC shifts it a day earlier for anyone west of Greenwich. It also counts whole calendar days instead of elapsed hours, so a daylight saving change never adds or removes a day from your totals. The second field is the part most people miss. Set it to a future date to answer "how old will they be on the day of the wedding", or to a past date to answer "how old was I when that happened". Every calculation runs in your browser: no date you type is uploaded, stored or logged.
Frequently asked questions
How is age calculated in years, months and days?
Take the difference in years, then the difference in months, then the difference in days. If the day of the month has not been reached yet, borrow the number of days in the previous calendar month and take one off the month count. If the month has not been reached yet, borrow twelve months and take one off the year count. This tool uses the real length of each month, so the result matches what a registry office or a visa form works out by hand.
Does the calculator handle leap years and 29 February birthdays?
Yes. Leap days are counted in the total days figure because the calculation walks the real calendar rather than a 365 day approximation. For a 29 February birthday, the next birthday falls on 1 March in a common year, which is the convention most official bodies use, and on 29 February in a leap year.
Can I calculate an age on a date other than today?
Yes. Change the second field to any date, past or future. That covers the questions a plain age tool cannot answer, such as how old a child will be on the first day of a school term, how old someone was on a particular date in the past, or what age a policy holder reaches at renewal.
Why does another age calculator give me a different answer by one day?
Almost always because the other tool parses your date of birth as UTC midnight and then reads it back in your local timezone, which shifts it a day earlier for anyone in the Americas. This tool treats both dates as plain calendar dates in your own timezone, so the weekday of birth and every day count stay correct wherever you are.
What does the total days figure include?
Every calendar day from the day after the date of birth up to and including the comparison date, leap days included. It is a whole day count rather than an elapsed hours count, so a clock change never shifts it.
Is my date of birth sent anywhere?
No. The whole calculation runs in JavaScript on your own device. Nothing is uploaded, nothing is written to a database, and nothing is saved to a cookie. Close the tab and the dates are gone.
How do I work out how many days until my next birthday?
Enter your date of birth and leave the second field on today. The last card shows the number of days remaining and the exact date and weekday that your next birthday falls on.