How Old Am I?
One birth date in, your exact age out, down to the day.
To find exactly how old you are, subtract your birth date from today's date, borrowing months and days the way calendars work. Someone born June 15, 1990 is 36 years, 3 months, and 20 days old on October 5, 2026, and has lived 13,261 days. The calculator above does the borrowing for you and adds your birth weekday and next-birthday countdown.
Why the simple subtraction fails
Subtracting just the years gives 36 for our example, which is right only by accident of the calendar. Most of the year, year-only subtraction is off by one, and it never gives months and days.
Proper age math borrows like elementary subtraction: negative days borrow the previous month's actual length, negative months borrow 12 from the year. That is what makes the answer exact instead of approximate.
What else your birth date tells you
The same date gives your birth weekday (June 15, 1990 was a Friday), your total days lived (13,261 as of October 5, 2026), and the countdown to your next birthday (253 days).
These are handy for forms that ask age in an unusual unit, for milestone birthdays, and for settling debates about who is older by how much.
Leap years and edge cases
February 29 birthdays are the classic edge case. In non-leap years the convention is to count from March 1, which keeps the years-months-days arithmetic consistent.
Month lengths are taken from the real calendar, 28 to 31 days, never an average 30.44. That is the difference between an exact age and an estimate.
Skip the arithmetic
Get your exact age in seconds with the free calculator.
Exact age questions
How can I find out exactly how old I am?
Subtract your birth year, month, and day from today's date, borrowing the previous month's days when the day goes negative and 12 months when the month goes negative. The calculator above does this instantly and accurately.
Why does my age change on my birthday and not January 1?
Age measures completed years of life since the day you were born. You complete another year on your birthday, not on New Year's Day, which is why the count changes on that date.
How many days old is a 30 year old?
Roughly 10,957 days for 30 plain years, plus one extra day for each leap day lived through, usually 7 or 8. The exact count depends on the specific birth date, which is why the calculator counts real calendar days.