How the age calculator works
Age is counted the way people normally say it: full years since the last birthday, then full months, then remaining days.
Months = complete months since the last birthday
Days = days since the last month boundary
When the day of the month has not yet been reached, the calculator borrows the length of the previous month, so the result works across months of 28 to 31 days. Total days are a straight count between the dates, including every leap day. People born on February 29 usually celebrate on February 28 or March 1 in non-leap years; this calculator uses March 1 for the next-birthday countdown in that case.
Worked example
Someone born on May 15, 1990 is 36 years, 4 months and 29 days old on October 14, 2026. They have lived 13,301 days, or 1,900 weeks, and their next birthday is 213 days away, on May 15, 2027.
Frequently asked questions
How is exact age calculated?
Count full years since birth, then full months since the last birthday, then the remaining days.
How many days old am I?
Enter your birth date; the total days line counts every day since, including leap days.
What about leap-day birthdays?
In non-leap years, the countdown treats March 1 as the birthday.
Can I calculate age on a past date?
Yes. Set the second date to any date after the birth date.
Updated October 2026. Results are estimates for education, not financial or medical advice. All math runs in your browser; nothing you type is sent anywhere.