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Age Calculator
Calculate age from a date of birth in years, months, and days, on today or any other date.
The calendar date of birth
The day to count the age on. It starts as today on this device.
Enter a birth date and an age-on date.
Enter a birth date and an age-on date.
This age calculator finds how old someone is from a date of birth. Enter the birth date and the date to count on. That second date starts as today on your device, and you can change it to any other day. The result is years, months, and days on the real calendar, plus total months, total weeks, total days, and the next birthday. A baby's age is the same count, read in months and weeks. A February 29 birthday is observed on March 1 in a year that is not a leap year.
Age on a date you choose
An age calculator by date of birth needs two calendar dates: the day someone was born, and the day you want the age for. The second date starts as today on this device. The Use today button puts that local date back if you changed it. To answer how old is, or how old am I, enter the birth date. The page does not look up a name.
The count uses the calendar, not a division by 365. Full years come first. If the birthday in the age-on year has not happened yet, the year count is one less. Months work the same way. If the day number has not arrived, borrow the real length of the previous month, which is 28, 29, 30, or 31, and then subtract. Born on January 1, 2000, the age on September 24, 2026 is 26 years, 8 months, and 23 days. A date has no clock time, so the result stops at days.
A baby's age in months and weeks
Families usually say a baby's age in months or weeks rather than years. Completed months are the years times 12, plus the months, with the leftover days kept beside them. Total weeks split the total days by 7 and keep the leftover days. Both totals are exact.
A baby born on January 10, 2026 is 0 years, 8 months, and 14 days old on September 24, 2026. That is 8 months and 14 days. The same span is 257 days, which is 36 weeks and 5 days. Change the age-on date to see the age on a checkup day or on a future birthday.
February 29 birthdays
February 29 is on the calendar only in a leap year. In any other year this calculator uses March 1 as the anniversary, not the last day of February. Someone born on February 29, 2020 is still 0 years, 11 months, and 30 days old on February 28, 2021. On March 1, 2021 the age is 1 year, 0 months, and 0 days, and the result says it is their birthday. In a leap year the birthday stays on February 29.
Frequently Asked Questions
How old is someone if I know the date of birth?
Enter the date of birth and the age-on date. The calculator answers from those two dates only. It does not look up a person, a celebrity, or a name. How old am I uses the same steps: your birth date, and today or another date you pick.
How do I find an age on a date that is not today?
Change the age-on date to the day you care about, in the past or the future. The age updates for that calendar date. Use today puts the age-on date back to today's date on this device. That local date can differ from a date based on another time zone.
How old is a baby in months and weeks?
Read the total months and total weeks under the year, month, and day age. A birth date of January 10, 2026 and an age-on date of September 24, 2026 give 8 months and 14 days. The same span is 36 weeks and 5 days, which is 257 days.
What if the age-on date is before the birthday?
The calculator says the age-on date is before the birthday. It does not show a negative age. Pick an age-on date on the birth date or after it. On the birth date itself the age is 0 years, 0 months, and 0 days, and the result says it is their birthday.
What happens to a February 29 birthday when the year is not a leap year?
The anniversary is March 1. February 28 is still the day before the birthday. Someone born on February 29, 2020 turns 1 on March 1, 2021. On February 28, 2021 the age is 0 years, 11 months, and 30 days. When February 29 is on the calendar, the birthday stays on that day.