CalcThai
calcthai.com · Thai Land Area Converter
General & conversion
Thai Land Area Converter
1 rai = 1,600 m², about 0.4 acres. Convert rai, ngan and square wah to square metres both ways, read a 1-2-50 deed, and value a plot per square wah.
Thai land unit conversion table
| Unit | Equals | Square metres |
|---|---|---|
| 1 rai | 4 ngan, or 400 sq wah | 1,600 |
| 1 ngan | 100 sq wah | 400 |
| 1 square wah | 4 square metres | 4 |
| 1 hectare | 6 rai 1 ngan | 10,000 |
| 1 acre | about 2.53 rai | 4,046.86 |
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Thailand measures land in rai, ngan and square wah — a system used nowhere else in the world. If you are looking at property here, you will meet these units immediately: every title deed, every listing and every agent quotes them, and almost none of them convert to square metres for you.
This converter works in both directions and will also calculate a plot value from the price per square wah, which is how urban land is normally priced in Thailand.
How it works
How the units relate. The Thai system is easy to remember because the multiples are clean. One rai is four ngan. One ngan is one hundred square wah. One square wah is four square metres. Multiply them through and one rai is four hundred square wah, or exactly 1,600 square metres.
Where the square wah comes from. A wah is a traditional Thai unit of length equal to two metres. A square wah is therefore a square two metres on each side — four square metres exactly.
Reading a title deed. Land area on a Thai title deed is always written as rai-ngan-wah in that order. A deed reading 1-2-50 means 1 rai, 2 ngan and 50 square wah. Converted, that is 2,600 square metres: 1,600 for the rai, 800 for the two ngan, and 200 for the fifty square wah.
Land prices are usually quoted per square wah. In Thai property transactions the price is normally given in baht per square wah, especially in towns and cities. Large rural or agricultural plots are more often priced per rai. Converting between the two matters a great deal when you are comparing plots that were advertised in different units.
Against international units. One hectare is 10,000 square metres, which is about 6 rai and 1 ngan. One acre is about 4,047 square metres, or roughly 2.53 rai.
One point worth knowing if you are buying: foreign nationals generally cannot own land in Thailand in their own name, though they can own a condominium unit outright subject to the building’s foreign ownership quota. The rules around this are specific, so take proper legal advice before committing to anything.
Frequently asked questions
How big is 1 rai?
1 rai is 400 square wah, or exactly 1,600 square metres — roughly 0.4 acres. It works out from the units themselves: a rai is 4 ngan, each ngan is 100 square wah, giving 400 square wah, and each square wah is 4 square metres.
My title deed says 1-2-50. What does that mean?
It means 1 rai, 2 ngan and 50 square wah. That hyphenated format is the standard the Department of Lands uses, always in that order. Converted it comes to 2,600 square metres.
How do I convert a price per rai to a price per square wah?
Divide the price per rai by 400. Going the other way, multiply the price per square wah by 400. For example land at 2 million baht per rai is 5,000 baht per square wah. This conversion is essential when comparing plots advertised in different units, which happens constantly.
What can I build on 100 square wah?
100 square wah is 400 square metres, a comfortable size for a detached house. The buildable area is smaller than the plot though, because building control regulations set minimum setbacks from the boundary and a minimum open area. Check the local regulations and talk to an architect before designing anything.
Sources
Rates last verified 25 Aug 2026