After you so diligently studied very hard to learn and memorize all eleven Thai numbers (0 through 10 is 11 numbers, silly), you probably noticed that Thais rarely actually used Thai numbers. Was this all a waste? Is it even appropriate to use Thai numbers when writing? What other special rules are there when writing Thai numbers? I will admit these are very nit-picky Thai grammar rules, but I ran across some of them in a grammar book and thought it’d be useful yet easy knowledge for beginners to list them all now.

Let’s start with the basics.

When writing Thai, when should you use Thai numbers? And when should you use Arabic (1, 2, 3, etc.) and Roman (I, II, IV, etc.) numbers? The general rule of thumb is, if you aren’t sure, use Arabic numbers.

Arabic numbers should be used in articles and papers, when listing prices, and when doing anything that involves math (calculating something) or science. Romanized numerals can also be used for science related purposes, such as categorizing sections in a scientific research paper.

Thai numbers should only be used for the Thai lunar calendar and for abbreviations of things that use Thai numbers. Thai numbers can be used for when taking notes of things. It can also be used for room and building numbers, however this is typically avoided given the large farang population in Thailand which accesses these places. Thai numbers can also be used for chapter and page numbering in a book, and for license plates.

Should numbers be separated by a space away from other words? The answer is yes, always, except when the number is part of an abbreviation or name.

For example:

ราคา 500 บาท          price 500 baht    (separated by spaces)

น้ำท่วมสูง 1-2 เมตร   flood waters up to 1-2 meters    (separated by spaces)

วิตมินบี12                 vitamin B12         (NOT separated by a space)

โนเกีย เอ็น9               Nokia N9              (NOT separated by a space)

And just like in English:

– Use commas to separate every 1000 in a number (for example 1,000,000). But do not use commas for years.

– Use a period for decimals, such as 0.13 or ๑๒.๐๘.

– If there are numbers in a sentence, it’s usually better to write it as ‘one or two numbers’, not ‘1 or 2 numbers’.