How it works
Pick your date of birth (enter the year in B.E. or A.D.) and your age as of today appears instantly. To get your age on another date, change "Age on".
Formula
Age = full years + full months + remaining days from birth to the reference date
Total days = reference date − date of birth (real calendar, including leap years)
FAQ
How is age in years, months and days counted?
Full years and months since birth are counted first, then the remaining days up to the reference date. If the birth day does not exist in a month (born on the 31st, month has 30 days), the last day of that month counts as the monthly anniversary.
When does someone born on 29 February get a year older?
In years without 29 February, this calculator treats 28 February as the birthday.
Can I enter the year in the Thai Buddhist Era?
Yes. Choose B.E. or A.D. at the end of the date. It is converted automatically and your choice is remembered next time.
Can I calculate age on a past or future date?
Yes. Change "Age on" to any date, such as a job application, retirement or exam date. A copied link keeps that date too.
Related tools
- Your Life in WeeksIf you live to a given age, how many weeks have you lived and how many are left? See your whole life as a grid where one box is one week.
- Thai Year Converter (B.E. ↔ A.D.)Convert Thai Buddhist Era (B.E.) years to Gregorian (A.D.) and back, or convert a full date and see the weekday.