How to use the age calculator
- Enter the date of birth.
- Leave Age on as today, or change it to find the age on a past or future date, such as a test date or a deadline.
- Read the exact age in years, months and days, the totals in months, weeks, days and hours, and the countdown to the next birthday.
How age is calculated
The calculator counts full years since the birth date, then full months since the last birthday, then the remaining days. When the day of the month hasn't been reached yet, it borrows the length of the previous month, which is the standard way to count age.
Example: born March 15, 2000. On October 6, 2026 that is 26 full years (March 15, 2026), 6 full months (September 15, 2026) and 21 days, so 26 years, 6 months and 21 days.
Chronological age for schools and tests
Psychologists and schools use chronological age to score assessments and decide grade placement. Enter the child's birth date and set "Age on" to the test date to get the exact years, months and days. Most scoring manuals ignore the extra days or round them as their instructions say, so check the test manual.
Frequently asked questions
How is age calculated?
Age is the number of full years since your date of birth, plus the months and days since your last birthday. Someone born on March 15, 2000 is 26 years, 6 months and 21 days old on October 6, 2026.
What is chronological age?
Chronological age is the exact time since birth in years, months and days. Schools and psychologists use it to score tests. Enter the birth date and set "Age on" to the test date to get it.
How do I find my age on a specific date?
Change the "Age on" date. The calculator then shows how old you were, or will be, on that day, which helps with forms, eligibility rules and school cut-off dates.
What if I was born on February 29?
In years without February 29, the calculator treats February 28 as your birthday for the countdown. Your age still goes up by one year each year.
How many days old am I?
The calculator shows your age in total days, weeks, months and hours, and the date of your 10,000th day, a milestone many people celebrate at about 27 years old.