Rai, ngan, and tarang wa

{{Short description|Thai units of area}} {{DISPLAYTITLE:''Rai'', ''ngan'', and ''tarang wa''}} {{Redirect|Ngan}} {{Use dmy dates|date=January 2024}} {{Use British English|date=January 2024}} The '''''rai''''',{{efn|{{langx|th|ไร่}}, {{IPA|th|râj|pron}}.}} '''''ngan''''',{{efn|Also spelled ''ngaan''; {{lang|th|งาน}} {{IPA|th|ŋɑ̄ːn|}}.}} and '''''tarang wa''''' or '''square''' '''''wa'''''{{efn|Also ''tarang wah'' or square ''wah''; {{lang|th|ตารางวา}} {{IPA|th|tɑ̄ː.rɑ̄ːŋ wɑ̄ː|}}.}} are customary Thai units of area, used in the measurement of land. They are defined as exactly 1,600, 400, and 4 square metres, respectively (17,222, 4,306, and 43 sq ft).<ref name="Commercial Directory" />

The ''tarang wa'' (square ''wa'', ''tarang'' meaning 'grid') is derived from the area of a square with sides of 1 ''wa'' (the Thai fathom). 1 ''ngan'' ('work') is equal to 100 square ''wa'', and 1 ''rai'' ('field' or 'plantation') equals 4 ''ngan'' or 1 square ''sen''.<ref name="Commercial Directory">{{cite book |title=Commercial Directory for Thailand B.E. 2496-97 (1953-54) |date=1953 |publisher=Department of Commercial Intelligence, Ministry of Economic Affairs |page=3{{hyphen}}11 |url=https://books.google.com/books?id=w7QHtC8GhSQC&pg=RA2-PA11 |language=th,en}}</ref> The units were standardised in square metres when Thailand (then Siam) adopted the metric system in 1923,<ref>{{cite book |author1=Bureau of Weights and Measures |editor1=จรินทร สุทธนารักษ์ |editor2=สาธิต ชูสุวรรณ |title=นานาสาระชั่งตวงวัด |publisher=Central Bureau of Weights and Measures |url=https://www.dit.go.th/region/SITE/CBWM23/PUBLICATIONS/1_%E0%B8%99%E0%B8%B2%E0%B8%99%E0%B8%B2%E0%B8%AA%E0%B8%B2%E0%B8%A3%E0%B8%B0%201%20B-W%20Reduced%20Ver%201.0.pdf |language=th |chapter=ประวัติการชั่งตวงวัดของประเทศไทย}}</ref><ref>{{cite web |title=History of Weights and Measures in Thailand |url=http://nwmc.go.th/history_eng.html |website=Northern Weights and Measures Center |archive-url=https://web.archive.org/web/20200222154748/http://nwmc.go.th/history_eng.html |date=2004 |archive-date=2020-02-22|url-status=dead}}</ref> although the Royal Survey Department was already reported in 1908 to be using the metre-based conversion for its cadastral maps.<ref>{{cite book |last1=Wright |first1=Arnold |last2=Breakspear |first2=Oliver T. |title=Twentieth century impressions of Siam: its history, people, commerce, industries, and resources, with which is incorporated an abridged edition of Twentieth century impressions of British Malaya |date=1908 |publisher=London [etc.] Lloyds Greater Britain Publishing Company, Ltd. |page=126 |url=https://archive.org/details/twentiethcentury00wrigrich/page/n129/mode/2up}}</ref>

The units are commonly used for cadastre and property matters, and official and legal documents express areas of land in such units.<ref>{{cite web |title=คำศัพท์ภาษาอังกฤษด้านการที่ดิน (Terminology of the Department of Lands) |author1=สำนักงานบริหารโครงการพัฒนากรมที่ดิน และเร่งรัดการออกโฉนดที่ดินทั่วประเทศ |url=https://www.dol.go.th/km2/Documents/do206.pdf |publisher=Department of Lands |access-date=7 January 2024 |language=th,en |date=September 2011}}</ref> They are sometimes notated in the abbreviated format ''rai''-''ngan''-''tarang wa'', e.g. "4-2-25 ''rai''", which means "4 ''rai'', 2 ''ngan'', and 25 ''tarang wa''", though this is discouraged by some government documents.<ref>{{cite web |title=คำสั่งจังหวัดเชียงใหม่ ที่ 1/2528 เรื่อง แก้ไข (เนื้อที่ รูปแผนที่ หรือเนื้อที่และรูปแผนที่) ในโฉนดที่ดิน |url=https://www.dol.go.th/survey/DocLib1/30/30-2170.PDF#page=13 |publisher=Department of Interior |access-date=7 January 2024 |language=th |date=1985 |quote=หมายเหตุ การเขียนเนื้อที่ 6 ไร่ 3 งาน 06 ตารางวา ไม่ควรเขียนเป็น 6-3-06 ไร่}}</ref>

{|class="wikitable" |+Unit conversions |- !Unit !!Derivation !!Relative !!SI (or other metric) !!US or UK customary |- | ''Tarang wa'' ||Square ''wa'' || ||4 m2 ||43 sq ft |- | ''Ngan'' |||| 100 ''tarang wa'' ||400 m2 ||4,306 sq ft |- | ''Rai'' ||Square ''sen'' ||4 ''ngan'' or 400 ''tarang wa'' ||1,600 m2 (16 ares) ||17,222 sq ft (0.4 acres) |}

==Notes== {{notelist}}

==References== {{reflist}}

Category:Thai units of measurement Category:Units of area