Using a new or in this case an old measurement system can sometimes be a daunting task. We here at Shambhala Realty have put together a short piece that should make understanding the Thai Measurement System and converting between it and the Metric System a lot easier. We will be using the Metric system as a point of reference, as it is the System adopted by Thailand.

In regards to measuring the area of property in Thailand, there are three main measurements that you’ll need to remember; Tarang-Wah, Ngan and Rai. However it is first necessary to understand the measurement ‘Wa’ and its corresponding value, before moving on to the other measurements.  The ‘Wa’, or sometimes ‘Wah’, is a unit of length equating to 2 meters, “the verb ‘Wa’ means to outstretch one’s arms” (Wiki), the traditional measurement was based on the distance between the fingertips of one hand and those of the other.  ‘Tarang’ translated to English means ‘square’, so Tarang-Wah simply means ‘Wa squared’. Therefore the measurement Tarang-Wah equates to 4m2. The Ngan is a unit of measurement equating to 400m2; 100 Tarang Wa. The Rai is the largest measurement between the three, equating to 1600m2; 4 Ngan. Apologies for the barrage of measurements, just a little more to go. To make converting between the Metric System and the Thai Traditional System easier we advise beginning with the ratio of a square Wah or Tarang Wa compared to that of a square meter. We can calculate that the ratio between the two measurements is 1:4 or ¼ , therefore all that needs to be done when converting sq. m. to Tarang  Wah is to multiply the unit in sq. m. by ¼ , to achieve the opposite simply invert ¼ to 4/1 and multiply it by your unit in Tarang Wah.

Converting from Ngan to sq. m. is relatively straightforward, we again, calculate the ratio between a Ngan and a sq. m.; 1:400. Using the ratio we can convert 6000 sq. m. to 15 Ngan for example, by dividing 400 from 6000. We can also convert 4 Ngan to 2400sq. m. by multiplying 4Ngan by 400. 

The similar principle can be applied to conversions between Rai and sq. m. However we use the ration 1:1,600 instead. Using these as a basis you can easily calculate between measurements of Wa, Tarang Wa and Rai in relation to sq. m.

Below is a table illustrating the basic conversions between The Thai and Metric Measurements of area.

1     4
100 1 0.25 400
400 4 1 1,600
800 8 2 3,200
1,200 12 3 4,800
1,600 16 4 6,400
2,000 20 5 8,000


Once you’ve grasped the ratios it will become relatively easy to use the Thai Measurement System in congruence with the Metric System. Don’t forget practice makes perfect so stay diligent.