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Everyday calculators

Age calculator

Type a date of birth, with the year in A.D. or in the Thai Buddhist Era, and see the exact age in years, months and days, the weekday you were born on, the zodiac year and how many days are left to the next birthday.

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How to use it

  1. Type the day of birth, choose the month and type the year. The year is A.D.; for a Thai Buddhist Era year choose "B.E." (a year already typed is turned into the other era for you).
  2. The age is worked out for today. Change that date for another day, such as the closing date of an application.
  3. The age shows as you type. Press "Copy" to paste it into a form.

How it is worked out

It counts the whole months from the birth to the chosen day (a month only counts once its day of the month is reached), splits them into years of 12 months, then counts the days left on the calendar. Born 15 March 1987, on 15 October 2026 the age is 39 years, 7 months, 0 days. When the day of birth is past the end of a month (such as the 31st), the last day of that month stands in.

B.E. = A.D. + 543. The zodiac year goes by the calendar year (2020 was a year of the Rat). To only turn a date from one era into the other, use the Thai date converter; to count the days between any two dates, use days between dates.

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Questions and answers

Can I type a Buddhist year?

Yes. Choose B.E. and type the year as it is; the calculator subtracts 543 for you. For a Gregorian birth year choose A.D.

How is a 29 February birthday counted?

In years without 29 February, this calculator takes 28 February as the birthday, so the new year of age starts on 28 February.

How are the months and days counted?

Whole years first, then whole months, then the days left. A month counts when the same day of the month comes round; if that month is shorter, its last day counts.