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Thai land measurement units (area) – Rai, Ngan & Tarang Wah

How is land measured in Thailand? Thai Land Measurement – the units used

Thai land measurement, after many years of living and working here in Koh Phangan’s real estate and construction sectors, we have gleaned a good understanding of both the Koh Phangan real estate and construction environments, and also its potentially confusing processes.

Some things which we now take for granted (using rai land measurement units for instance) may well be as alien to the uninitiated as, say, the planet Mars. In order to assist you to understand a little easier we have compiled some nuggets of information for your benefit, a fast-track program shall we say.

Please read on if you feel the need for some explanations…


What is a rai?

Thai Land Measurement #1 – Rai – ไร่

1,600m2 – 2.5 rai equal one acre

Thai land measurement - Rai

Thai land measurement – Rai

This is the largest of the units used at 1,600 m2. Personally, it helps to visualise a 40m x 40m square – although, of course, 1 rai of land is seldom a 40 x 40m square.

As a reference for you, one rai is the equivalent of these well known area measurements : –

  • 0.395 acres – 2.5 rai equals one acre
  • 0.16 hectares – 6.25 rai is equal to one hectare
  • 17, 222 square feet
  • 1, 913.6 square yards

To put this into perspective the largest average house sizes being built these days are 203 m2 and 206 m2 in the US and Australia respectively with the majority of European nations houses being less than 100 m2 in size. Add to this the fact that with a two-storey house then the footprint, meaning the size of land actually used in making the house would be approximately half this area. So you can see that a rai of land is easily enough land, maybe more than enough land, to make your dream Koh Phangan home.


What is a ngan?

Thai Land Measurement #2 – Ngan – งาน

400m2 – 4 ngan (4x 400m2) = 1 rai

Thai land measurement - Ngan

Thai land measurement – Ngan

One ngan is a quarter, 25%, of a rai. Again, personally, it helps to think of a ngan as its square, i.e. 20m x 20m.

As a reference for you one ngan is the equivalent of these area measurements : –

  • 0.099 acres – 10.1 ngan equals one acre
  • 0.04 hectares – 25 ngan is equal to one hectare
  • 4,305.56 square feet
  • 478.4 square yards

As we have seen above, one ngan would be easily enough land for making a very good sized house for you here on the beautiful island of Koh Phangan. Unfortunately it is often difficult to find plots of land for sale under one rai in size due to the local tradition of land subdivision although it is possible.


What is a tarang waa?

Thai Land Measurement #3 – Tarang Waa – ตารางวา

4m2 – 100 tarang waa (100 x 4m2) = 1 ngan (400m2)

Thai land measurement - Tarang Wah

Thai land measurement – Tarang Wah

The smallest of the measurement units used on a Thailand land deed. I have heard it said the basis of this measurement is from two outstretched arms, being approximately 2m. Tarang also means “square” in Thai, thus 2m x 2m is one tarang waa – or 2m squared (4m2).


There are various other specifically Thai measurements used in Thailand but they are not usually heard when discussing land. Other units are used for weight, length, and even boats, amongst others.

Hopefully you now have at least an idea of the commonly used terms when we talk about or advertise land here in Koh Phangan or Thailand. Commonly the land sizes can be noted like this :-

1 – 2 – 0

When you see this as denoting a land size it means 1 rai – 2 ngan – 0 tarang waa which in turn leads us to the calculation –

1 x 1,600 + 2 x 400 + 0 x 4 = 2,400 m2

Today the land offices, at least on Koh Phangan, use what is known as a Total Station. This highly technical piece of equipment is the industry standard for land surveying and construction set outs throughout the world. The Total Station measures distance and angles using a laser incorporated into it. This raw data can then be downloaded and made into a 3D survey. Needless to say this is great confirmation for the land owner/buyer and it is extremely useful and loved by architects. If your chosen piece of land is flat or not so large then it might be unnecessary but if your dream plot is rocky, sloped or large then the 3D survey is indispensable.

Now you know the Thai land measurement system and how to convert to square meters as well as other often used area measurement units. We hope that this will help you in your quest to find your perfect plot of land in your new Thailand or Koh Phangan adventure!

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