Thai Area Unit Converter

If you’re looking at land in Thailand for the first time, three words soon become familiar: Rai, Ngan, and Square Wah. They’re common on land listings and title deeds. If you’re used to acres or hectares, it can take a little practice to picture the area.

The first time someone told us a plot was “1-2-50,” Kris and I just nodded and pretended we understood. We didn’t. It took an embarrassingly long time and a lot of squinting at title deeds before I actually internalized what these numbers mean — and I’m Thai.

These customary units remain common for land plots. Condo-unit sizes and building floor areas are usually given in square meters (m²), so first check what the listing measures: the plot, the building, or a particular unit.

Thai Land Measurement at a Glance

Here’s the cheat sheet. Bookmark this table — it’s the one you’ll keep coming back to.

In Thai: rai = ไร่, ngan = งาน, and square wah = ตารางวา (often abbreviated ตร.ว.). Approximate square-foot equivalents are 43 ft² per square wah, 4,306 ft² per ngan, and 17,222 ft² per rai.

The relationship between them:

• 1 Rai = 4 Ngan = 400 Square Wah = 1,600 sqm
• 1 Ngan = 100 Square Wah = 400 sqm
• 1 Square Wah = 4 sqm

1 rai is approximately 0.395 acres, so about 2.53 rai make an acre. It is exactly 0.16 hectares, or 6.25 rai per hectare.

What Is a Rai?

Rai (ไร่) is a customary Thai land-area unit used for everything from farms to residential plots. One rai is exactly 1,600 m²; the Industrial Estate Authority of Thailand uses this conversion in its land information.

The farming associations make the word memorable, but a rai is a fixed area today. It does not depend on the work a farmer can do or the shape of the plot.

How Big Is 1 Rai?

“1,600 square meters” doesn’t land (pun intended) until you can picture it:

• As a square: 40 meters by 40 meters — about 131 feet on each side. A plot can have a different shape and still cover one rai.
• Football (soccer) pitch: About 22% of a 105 × 68 m playing field (7,140 m²).
• Tennis courts: About 6.1 doubles-court rectangles by area, excluding run-off space and facilities.
• House plots: A 50–100 square wah plot is 200–400 m², or one-eighth to one-quarter rai. One rai gives you four times the area of a 100-square-wah plot.

Understanding Ngan and Square Wah

Ngan and square wah are useful when comparing smaller residential plots. Listings may give a single unit or combine all three.

Traditional units and metric units coexist. Land listings often use rai, ngan, and square wah; a project brochure may also give the site area in m². Condo-unit sizes typically use m². For example, Sansiri’s THE BASE Height Chiangmai brochure lists unit sizes in m² and square feet separately from the project’s land area. A building’s total floor area can span several stories and is not the same as the land beneath it.

Ngan (งาน) — The Quarter Rai

Ngan (งาน) literally means “work” in Thai. It’s the middle unit:

• 1 Ngan = 100 Square Wah = 400 sqm
• There are exactly 4 Ngan in 1 Rai

As a square: 20 meters by 20 meters (about 66 feet on each side).

A 1-ngan plot has 400 m² of land. That could allow space for a house, driveway, and garden, but the usable layout depends on the plot’s shape, access, and building requirements — the area alone does not tell you what fits.

Square Wah (ตารางวา) — The Building Block

Square wah is useful for describing small plots and the remainder in a three-part land measurement.

Wah (วา) is a traditional Thai length unit, now exactly 2 meters (about 6.56 feet). Thinking of an armspan can help you remember the idea, but a person’s actual reach is not a precise measure.

Square Wah is that length squared: 2m x 2m = 4 square meters (about 43 sq ft).

100 square wah make a ngan; 400 make a rai. For example, a house plot of 50–80 square wah covers 200–320 m² of land. A condo advertised as 32–40 m² describes the unit’s area, not a private plot of 8–10 square wah.

How to Read Thai Land Sizes (The X-X-X Format)

In Thailand, land area is written in a three-part format: Rai-Ngan-Square Wah. Something like 2-1-50 reads left to right, largest to smallest:

• 2 Rai
• 1 Ngan
• 50 Square Wah

To convert to square meters, multiply each part by its metric equivalent and add:

You’ll see this format on title deeds, listings, and land office documents. A few more examples:

• 0-1-25 = 0 + 400 + 100 = 500 sqm (~0.12 acres).
• 0-3-50 = 0 + 1,200 + 200 = 1,400 sqm (~0.35 acres).
• 4-2-0 = 6,400 + 800 + 0 = 7,200 sqm (~1.78 acres).
• 15-0-0 = 24,000 sqm (~5.93 acres).

The same arithmetic works when square wah includes a decimal. For example, 2-2-99.5 = 3,200 + 800 + 398 = 4,398 m². A Lopburi government report on land-title deeds records exactly this fractional square-wah amount.

In a normalized three-part value, the ranges are 0 ≤ ngan < 4 and 0 ≤ square wah < 100. Fractions such as 99.5 square wah are valid; 100 square wah carries into 1 ngan, and 4 ngan into 1 rai. A listing that simply says “400 square wah” is also 1 rai — the single-unit amount does not have the same remainder limit.

Rai Calculator — Convert Thai Land Units

Return to the calculator to enter a single unit or the three parts from a listing. It converts the area without changing what the listing measures.

Quick Conversion Cheat Sheet

Thai to Metric: