A rai (Thai: ไร่ [râj]) 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).
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. The word also means plantation.
- "Units of Measurement". Thailand Guru, a service of Export Quality Services Co., Ltd. Retrieved 15 April 2007. (which uses the name 'waa' instead of 'dtaaraangwaa' for the 'square waa')
- "Thailand Information - Measurement". www.PureThailand.com. Retrieved 15 April 2007. (with spelling variants 'wah' and 'tara[a]ng wah' for 'waa' and 'dtaaraangwaa')