Age calculator
Enter a date of birth to see the exact age. You get years, months and days on today’s date or any other, the age in months, weeks, days and hours, the weekday of the birth and a countdown to the next birthday. It works for babies, children and adults.
Counts calendar dates only, so time zones can’t change the answer
Today’s date, or pick another, such as a school or visa cutoff date.
- Years
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- Months
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- Days
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Enter a date of birth to see the age.
Next birthday
Age in other units
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How age is calculated
The calculator counts the whole years since the date of birth, then the whole months since the last birthday, then the days left over. Someone born on March 15, 1990 is 36 years, 6 months and 16 days old on October 1, 2026.
Months are counted from the birth date each time. When a month doesn’t have that day, its last day is used: one month after January 31 is February 28, or February 29 in a leap year.
The totals count every day between the two dates. Weeks are the days divided by 7, and hours and minutes treat each day as 24 hours, as if the birth were at midnight.
Dates, not times
Only the calendar dates are used, never the time of day, so the same two dates give the same answer in every time zone and daylight saving time can’t move it. “Today” is today’s date on your device. Everything is worked out in your browser, and the dates you enter aren’t sent anywhere.
Chronological age for tests and school
Chronological age is the exact time since birth, as opposed to a developmental or mental age. Psychologists, speech therapists and teachers use it to score standardized tests, often written as years and months, such as 7;4 for 7 years and 4 months. Some test manuals ask you to count every month as 30 days when you subtract by hand, so their answer can differ from this one by a day or two. If the manual gives a rule, follow it.
Age calculator for babies and children
Babies are usually described in weeks for the first few months, then in months until about age 2. The totals show both: a baby born on June 20, 2026 is 3 months and 11 days, or 14 weeks and 5 days, old on October 1, 2026.
Questions about calculating age
How do I calculate age from a date of birth?
Subtract the birth year from the current year, and if the birthday hasn’t come yet this year, subtract 1 more. For the months, count the whole months since the last birthday, then the days since that date in the latest month. The calculator above does this for any two dates.
How do I calculate age from the birth year only?
Subtract the birth year from this year. That’s the age after this year’s birthday; before it, the age is 1 less. Someone born in 1990 is 36 in 2026 once the birthday has passed, and 35 before that.
How old is someone born on February 29?
In years without a February 29, this calculator counts the birthday on February 28. Laws differ, and some places treat March 1 as the birthday in those years. If it matters for a document or a deadline, check the rule that applies.
What is corrected age for a premature baby?
Corrected age, or adjusted age, is a premature baby’s age minus the number of weeks the baby was born early. A baby born 8 weeks early who is 6 months old has a corrected age of about 4 months. Doctors use it to check growth and development until about age 2 or 3. To see it here, enter the due date as the date of birth: the years, months and days are then the corrected age, but the weekday and next birthday shown are for the due date, not the real birthday.
Why do age calculators sometimes disagree by a day?
Months have different lengths, so the days left over depend on how a calculator counts a month from a date like January 31. This one counts whole months from the birth date and uses the last day of a shorter month. Totals in days and weeks don’t depend on that, so they match in every correct calculator.