World Library  
Flag as Inappropriate
Email this Article

Rai (unit)

Article Id: WHEBN0010317307
Reproduction Date:

Title: Rai (unit)  
Author: World Heritage Encyclopedia
Language: English
Subject: Ban Mae, 2011 Southeast Asian floods, Thai Sikh International School, Thai units of measurement, Laplae District
Publisher: World Heritage Encyclopedia

Rai (unit)

A rai (Thai: ไร่  ) is a unit of area, equal to 1 square sen (เส้น) or 1,600 square metres (40 m × 40 m), and is used in measuring land area for a cadastre or cadastral map.[note 1] 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 (Thai: งาน  ) or 400 tarangwa (Thai: ตารางวา  ) aka square wa.

It is commonly used in Thailand and equals 16 ares, another unit that is based on the metre and commonly used in several countries. Although recognized by the SI, its use is not encouraged. The word also means plantation.

See also


  • "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". Retrieved 15 April 2007.  (with spelling variants 'wah' and 'tara[a]ng wah' for 'waa' and 'dtaaraangwaa')


  1. ^ Giblin, R. W. (2008) [1908]. "Chapter Royal Survey Work.". In Wright, Arnold; Breakspear, Oliver T. Twentieth century impressions of Siam (65.3 MB). London&c: Lloyds Greater Britain Publishing Company. at Work of the Deaprtment, p.126, para. 5. Retrieved January 28, 2012. It so happens that 40 metres or 4,000 centimetres are equal to one sen, so all cadastral plans are plotted, drawn, and printed to a scale of 1:4,000. 

See also

  • 1 E+3 m² for a comparison with other areas
  • Area metric conversion, British and U.S., Japanese, Chinese, Thai, old French, old Spanish, old Russian, etc.
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.