How do I calculate my exact age in years, months and days?

Enter your date of birth: the tool counts the birthdays you have passed, then the months since the last one, then the remaining days, following the Thai Civil Code. It also gives the total in days, hours and minutes, and your age on any other date, handy for a form that asks for your “age on the closing date”.

How do I convert a Thai year (พ.ศ.) to a Western year (ค.ศ.)?

Subtract 543: 2530 − 543 = 1987. The other way round, add 543. The exception: for a January to March date before 1941, written at the time, subtract 542, because the Thai year then began on 1 April. The converter applies this rule automatically.

Why did the year 2483 last only nine months?

Until 1940, the official Thai New Year fell on 1 April. An announcement in December 2483 moved it to 1 January from 2484 onwards. The year 2483 therefore began on 1 April 1940 and ended on 31 December 1940: January, February and March 2483, as people counted then, never existed.

What is “ย่าง” age?

It is the year of life you have entered. Someone who has completed 29 years is living their 30th year, so they are “ย่าง 30”. Some Thai procedures count this way, such as military registration, which concerns men in the year they “enter” their 18th year.

I don't know my day or month of birth: how is my age counted?

Section 16 of the Thai Civil Code covers this: if only the month is known, the birth is set on the 1st of that month; if only the year is known, on 1 January of that year. Choose “day unknown” or “month unknown” in the tool and it applies the rule.

At what age do Thai civil servants retire?

At 60, but not on their birthday: retirement takes effect on 30 September, the end of the fiscal year in which they complete 60 years. Someone born in November therefore retires on the 30 September after their 60th birthday. The tool works out the date; confirm it with your HR department.

I was born on 29 February: when do I turn a year older?

In common years, the most widespread custom is to celebrate on 28 February, and that is the tool's convention. Thai law sets no specific rule; for an official document, ask the office concerned how it counts.

Free

Age Calculator and Thai Year Converter (พ.ศ. ↔ ค.ศ.)

How old are you exactly, when will you reach your 10,000th day, and which Western year is “2 March 2477”? Enter your date of birth to get your age to the day, a live counter, a countdown to your birthday and the key dates of a life in Thailand. The converter switches between Thai eras, reads a date written the Thai way and applies the rule most calculators forget: before 1941, the Thai year began on 1 April.

Free, no sign-up, nothing stored

Choose at least your year of birth to see the result.

How it works

Age is counted as section 16 of the Thai Civil and Commercial Code (ป.พ.พ.) provides: from the day of birth. A year is completed on each birthday, a month on the same day of the following month, then the remaining days are counted. If you only know your month of birth, the law sets the birth on the 1st of that month; if you only know the year, on 1 January. The tool applies this rule when you choose “day unknown” or “month unknown”. A 29 February birthday is celebrated on 28 February in common years. Everything runs in your browser and nothing is sent anywhere.
Thais also speak of “ย่าง” age (the year of life you have entered: at 29 completed years you are “ย่าง 30”) and of age by year, the simple difference between the years (2569 − 2530 = 39), which people work out in their heads and which is one year ahead of the exact age until the birthday comes. The 12-year cycles of the zodiac (รอบ) mark the big celebrations: 5 รอบ at 60, 6 at 72, 7 at 84. Age 25 (เบญจเพส) is, according to popular belief, a testing year, and many people make merit.
The Thai Buddhist Era (พ.ศ., BE) runs 543 years ahead of the Common Era (ค.ศ., AD). The other eras follow the formulas taught in Thai schools: RS + 2324, CS + 1181 and MS + 621 give the BE year. The Rattanakosin Era (ร.ศ.), counted from the founding of Bangkok in 1782, was used in official documents from 1889 (RS 108) to 1912; the Lesser Era (จ.ศ.) before it, and the Saka Era (ม.ศ.) in old inscriptions. For a full date, the tool also gives the Hijri date (ฮ.ศ.) from the Umm al-Qura calendar.
The trap with old dates: from 1889 to 1940, the official New Year fell on 1 April. The government moved New Year to 1 January from 2484 (1941), so the year 2483 lasted only nine months, from 1 April to 31 December 1940. A January to March date written before 1941 carries the year that began the previous April: subtract 542, not 543. King Rama VII's abdication, dated 2 March 2477, therefore took place on 2 March 1935. Historians sometimes rewrite it as “2 March 2478” in today's style, and the tool shows you both readings.
The legal ages shown come from the laws in force: ID card at 7 (ID Card Act, amended in 2554), work at 15 (Labour Protection Act, section 44), voting at 18 and standing for MP at 25 (2560 Constitution, sections 95 and 97), marriage at 18 (Civil Code, section 1448, as amended by the 2567 marriage equality law), majority at 20 (sections 19 and 20), no alcohol or tobacco sales under 20 (acts of 2551 and 2560), a 110 cc motorcycle licence at 15 and a temporary driving licence at 18 (Department of Land Transport), Social Security old-age pension at 55, senior status and allowance over 60 (Older Persons Act 2546), and civil service retirement on 30 September of the fiscal year in which you turn 60 (Government Pension Act 2494). Rules change: check with the relevant office before any formality.
Sources: Thai Civil and Commercial Code (sections 16, 19, 20, 1448), Constitution of the Kingdom of Thailand 2560, Royal Thai Government Gazette (ราชกิจจานุเบกษา), Department of Land Transport, Social Security Office, Ministry of Interior; for calendar history, the history columns of Silpa Wattanatham (ศิลปวัฒนธรรม) and Khaosod on the 2483 New Year change. Dates before 1889 remain approximate: the official year then followed the lunisolar calendar and changed around Songkran.

These tools give general information. They do not replace the advice of a doctor or a qualified professional.

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Frequently asked questions

How do I calculate my exact age in years, months and days?: Enter your date of birth: the tool counts the birthdays you have passed, then the months since the last one, then the remaining days, following the Thai Civil Code. It also gives the total in days, hours and minutes, and your age on any other date, handy for a form that asks for your “age on the closing date”.
How do I convert a Thai year (พ.ศ.) to a Western year (ค.ศ.)?: Subtract 543: 2530 − 543 = 1987. The other way round, add 543. The exception: for a January to March date before 1941, written at the time, subtract 542, because the Thai year then began on 1 April. The converter applies this rule automatically.
Why did the year 2483 last only nine months?: Until 1940, the official Thai New Year fell on 1 April. An announcement in December 2483 moved it to 1 January from 2484 onwards. The year 2483 therefore began on 1 April 1940 and ended on 31 December 1940: January, February and March 2483, as people counted then, never existed.
What is “ย่าง” age?: It is the year of life you have entered. Someone who has completed 29 years is living their 30th year, so they are “ย่าง 30”. Some Thai procedures count this way, such as military registration, which concerns men in the year they “enter” their 18th year.
I don't know my day or month of birth: how is my age counted?: Section 16 of the Thai Civil Code covers this: if only the month is known, the birth is set on the 1st of that month; if only the year is known, on 1 January of that year. Choose “day unknown” or “month unknown” in the tool and it applies the rule.
At what age do Thai civil servants retire?: At 60, but not on their birthday: retirement takes effect on 30 September, the end of the fiscal year in which they complete 60 years. Someone born in November therefore retires on the 30 September after their 60th birthday. The tool works out the date; confirm it with your HR department.
I was born on 29 February: when do I turn a year older?: In common years, the most widespread custom is to celebrate on 28 February, and that is the tool's convention. Thai law sets no specific rule; for an official document, ask the office concerned how it counts.

How it works

Frequently asked questions

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