Age Calculator
Exact age, total days lived and the next birthday from a date of birth.
How to use the Age Calculator
- Enter the date of birth.
- Leave the second date as today, or change it to see the age on any other day, past or future.
- Read the age in years, months and days, plus the totals in months, weeks, days and hours.
- Check the next birthday: its date, the weekday it falls on and how many days away it is.
About this tool
An age is a calendar calculation, not a division sum, which is why "how old am I in days" is harder than it looks. This calculator counts whole years first, then whole months, then the days left over, exactly as a calendar does. Someone born on 15 May 1990 is 36 years, 4 months and 18 days old on 3 October 2026, and has lived 13,290 days. The totals in months, weeks and hours come from the same count.
The second date can be anything you like: a wedding day, the first day of school, a date far in the future or one in history, so the tool also answers "how old was she when" and "how old will he be on". The weekday of birth is shown too, and the next birthday comes with its weekday, so you know whether the party lands on a Saturday.
Born on 29 February? In a year without one, the birthday is observed on 1 March by default, since that is when a full year has gone by, but you can switch it to 28 February if that is the custom where you live. A second date that falls before the birth is reported as a countdown to the birth rather than as a negative age.
Frequently asked questions
How are the years, months and days counted?
Whole years are counted from birthday to birthday, then whole months from the last birthday, then the days that remain. When the day of the month does not exist in a shorter month, for example the 31st in April, that monthly anniversary falls on the last day of the month.
When is a 29 February birthday celebrated in other years?
There is no single answer. Some countries treat 1 March as the legal birthday in a year without a leap day, while others use 28 February. This calculator uses 1 March unless you change the setting, which only appears for leap-day births.
Why is the number of hours always a multiple of 24?
Only the date of birth is used, not the time of day, so the hours are the whole days multiplied by 24. Counting from the exact minute would need the birth time and the time zone, which most people do not know precisely.
Is my date of birth saved or sent anywhere?
No. It is used only by the script running in this page and never goes to a server. It is not kept in local storage either, so it is gone as soon as you leave the page.
Does it work for dates before 1900 or far in the future?
Yes, for any year from 1 to 9999 in the Gregorian calendar used today. Bear in mind that dates before 1582 are shown in a calendar that did not yet exist at the time, so historical records may differ by a few days.