Age calculator
Shows completed age, years, months, and days, and the days until the next birthday.
When you want your age today, or your age on a chosen date.
Years, months, and days follow the real calendar, including month lengths and leap days. This is not a division by 365 or 30.
What this tool does
From a birth date and a reference date it shows the completed age, the years, months, and days, the total number of days, the weekday of birth, the next birthday, and how many days remain until it.
How the age is calculated
Years, months, and days follow the calendar. A year is not treated as 365 days, and a month is not treated as 30 days. Crossing a month uses that month’s length.
Leap years
A year with 29 February counts that day. Years divisible by 400 are leap years. Years divisible by 100 but not by 400 are not.
Born on 29 February
In a non-leap year the next birthday is treated as 28 February. It is not moved to 1 March, and the date is not left as 29 February.
Example
A birth date of 1 January 2000, measured on 1 January 2026, is a completed age of 26: 26 years, 0 months, and 0 days. The next day is 26 years, 0 months, and 1 day. The day before the birthday has not yet increased the completed age.
Questions
How old am I today?
Set the reference date to today. The completed age is your age today. The dates stay on this device and are not sent to analytics.
What is the difference between completed age and years, months, and days?
Completed age is how many birthdays have been reached. Years, months, and days are the calendar remainder up to the reference date.
Can I see my age on another date?
Change the reference date. If the birth date is after that date, nothing is calculated.