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How many square metres in a rai? Thai land units explained

1 rai = 1,600 m², 1 ngan = 400 m², 1 square wah = 4 m², as defined by Thailand's Weights and Measures Act B.E. 2542, and how to convert back to rai-ngan-wah.

By FileMyLove team1 min read

Thai land areas are written as three numbers, like 1-2-50: 1 rai, 2 ngan, 50 square wah.

Convert instantly with the rai-ngan-wah converter.

The Weights and Measures Act B.E. 2542 defines: 1 rai = 1,600 m², 1 ngan = 400 m², 1 square wah = 4 m². So 1 rai = 4 ngan = 400 square wah.

Rai-ngan-wah to square metres

rai × 1,600 + ngan × 400 + wah × 4. Example: 1-2-50 = 1,600 + 800 + 200 = 2,600 m².

Square metres back to rai-ngan-wah

Divide by 4 for total square wah (2,600 ÷ 4 = 650), take whole rai (400 wah each: 1, leaving 250), then whole ngan (100 wah each: 2, leaving 50): 1-2-50.

The legal area of a plot is the one on its title deed.

Sources

  1. Department of International Trade Promotion (copy of the Act)
    Weights and Measures Act B.E. 2542 (schedule, part B.(2))

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