A rai (Thai ไร่) is a unit of area, equal to 1,600 square metres (40 m × 40 m), used for measuring land area. Its current size is precisely derived from the metre, but is neither part of nor recognized by the modern metric system, the International System (SI).

The rai equals 4 ngaan or 400 tarangwa aka square waa.

It is commonly used in Thailand and equals 16 are, another unit based on the metre and as commonly used in several countries recognized though not encouraged by the SI.

References

• "Units of Measurement". Thailand Guru, a service of Export Quality Services Co., Ltd. Retrieved on 15 April 2007. (which uses the name 'waa' instead of 'dtaaraangwaa' for the 'square waa')
• "Information and advice when buying property in Thailand (Land Sizes)". Baan Thai Property Co. Ltd. Retrieved on 15 April 2007. (with spelling variant 'data-raang waa' for 'dtaaraangwaa')
• "Thailand Information - Measurement". www.PureThailand.com. Retrieved on 15 April 2007. (with spelling variants 'wah' and 'tara[a]ng wah' for 'waa' and 'dtaaraangwaa')

See also

• 1 E+3 m² for a comparison with other areas