Convert Ngan (งาน) to square feet

An exact unit, unusually

Most traditional land units in this atlas are approximations of a customary practice. The Thai system is different: when Thailand metricated, the square wah was fixed at exactly four square metres, and every unit above it inherited that exactness. One hundred square wah make a ngan of exactly 400 square metres, and four ngan make a rai of exactly 1,600 square metres.

Because the chain is exact, a conversion from ngan to square metres involves no judgement at all — the answer is a whole number for any whole number of ngan. This is why Thai land documents can be read directly by a surveyor working in metres without any of the reconciliation that a Nepali ropani or an Indian bigha demands.

How a Thai land area is actually written

A chanote states area as a triplet: rai, ngan, and square wah, in that order, with each field holding only its own place value. An area written "2-1-50" is two rai, one ngan and fifty square wah, which is 3,800 square metres. Readers new to the format frequently misparse it as a decimal or a date, and property listings compound the problem by dropping trailing zero fields.

The triplet never carries a fraction of a square wah, so the smallest area a deed can express is four square metres. Sub-divisions smaller than that are handled by adjusting the boundary description rather than the number, which is one reason Thai plot boundaries so often land on tidy metric figures.

Where the ngan matters commercially

Residential plots in Thai suburbs are quoted in ngan and square wah rather than rai, because a rai is larger than most house plots. A typical town house sits on fifty to eighty square wah; a detached house with a garden is often one to two ngan. Agricultural land, by contrast, is quoted in rai, and the ngan appears only as the remainder.

Land prices are usually advertised per square wah for residential and per rai for agricultural, so comparing two listings frequently requires converting through the ngan. Doing that conversion in the native chain — square wah to ngan to rai — is safer than routing through square metres, because it keeps every intermediate figure a whole number and makes a transcription error visible immediately.

Foreign buyers should note that the deed area, not the advertised area, is the legally operative figure. Marketing material rounds; the chanote does not.

Comparing Thai listings

Because residential land is advertised per square wah and agricultural land per rai, comparing two Thai listings usually means passing through the ngan. A plot advertised at a price per square wah can be scaled to a per-ngan figure by multiplying by one hundred, and to a per-rai figure by multiplying by four hundred, with no rounding at any step.

Keeping the arithmetic in the native chain is worth the small discipline it costs. Converting each listing to square metres first introduces decimals that hide transcription errors, whereas the traditional ladder produces whole numbers that visibly fail when a digit is dropped. Do the metric conversion once, at the end, for whoever needs it.

Common mistakes to avoid

• A deed area like "2-1-50" is rai-ngan-wah, not a decimal — misreading the format changes the area by a factor of four or more.
• Do not mix the ngan with the rai when comparing listings; residential prices are quoted per square wah, agricultural per rai.
• Square wah is an area (4 m²); wah on its own is a length (2 m). The two are routinely confused in translated listings.
• Advertised areas are rounded; only the chanote figure is legally binding.

Questions people ask about the Ngan (งาน)

How many square metres are in one ngan?

Exactly 400 square metres. The Thai land chain is exact by statute: one square wah is 4 m², one hundred square wah make a ngan, and four ngan make a rai of 1,600 m².

How do I read an area written as 3-2-25 on a Thai title deed?

It is three rai, two ngan and twenty-five square wah — 4,800 + 800 + 100 = 5,700 square metres. The three fields are always rai, ngan and square wah in that order.

Is the ngan still used in Thai property transactions today?

Yes. It is a statutory unit and appears on every chanote title deed. Metric areas are used in engineering drawings, but the deed itself is written in rai, ngan and square wah.