Thai units of measurement

Thailand adopted the metric system on 17 December 1923.^[1]

Before metrication, the traditional system of measurement used in Thailand employed anthropic units. Some of these units are still in use, albeit standardised to SI/metric measurements. When the Royal Thai Survey Department began cadastral survey in 1896, Director R. W. Giblin, F.R.G.S., noted, "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.^[2] The square wa, ngan and rai are still used in measurements of land area.

The baht is still used as a unit of measurement in gold trading. However, one baht of 96.5% gold bullion is defined as 15.16 grams rather than the generic standard of 15 grams. The baht has also become the name of the currency of Thailand, which was originally fixed to the corresponding mass of silver.

List of units

Unit	Thai spelling	Pronunciation (IPA)	Meaning equivalent	Relative equivalent	Metric equivalent
Length
Krabiat	กระเบียด	[krā.bìat]	Quarter of a finger		0.5208 cm
Nio	นิ้ว	[níw]	Siamese inch^[3] Cf. Digit (unit) finger (unit)	4 krabiat^[4]	2.083 cm
Khuep	คืบ	[kʰɯ̂ːp]	Span	12 nio^[4]	25 cm
Sok	ศอก	[sɔ̀ːk]	Cubit	2 khuep^[4]	50 cm
Wa	วา	[wāː]	Fathom (outstretched arms)	4 sok^[4]	2 m
Sen	เส้น	[sên]	Cf. Rope (unit) line of rope^[2]	20 wa^[4]	40 m
Yot	โยชน์	[jôːt]	Yojana	400 sen^[4]	16 km
Area
Tarang wa	ตารางวา	[tāː.rāːŋ wāː]	Square wa		4 m²
Ngan	งาน	[ŋāːn]		100 tarang wa	400 m²
Rai	ไร่	[râj]		4 ngan	1,600 m² (16 a)
Volume
Yip mue	หยิบมือ	[jìp mɯ̄ː]	Pinch		7.8125 mL
Kam mue	กำมือ	[kām mɯ̄ː]	Grain held in an enclosed hand	4 yip mue^[4]	31.25 mL
Fai mue	ฟายมือ	[fāːj mɯ̄ː]	Grain held in the palm	4 kam mue^[4]	125 mL
Thanan	ทะนาน	[tʰā.nāːn]	Coconut shell used for measuring	8 fai mue^[4]	1 L
Thang	ถัง	[tʰǎŋ]	Bucket	20 thanan^[4]	20 L
Sat	สัด	[sàt]	Measuring basket	25 thanan^[4]	25 L
Kwian	เกวียน	[kwīan]	Cartload	100 thang^[4]	2 m³
Weight/mass
Salueng	สลึง	[sā.lɯ̌ŋ]			3.75 g
Baht or Bat	บาท	[bàːt]		4 salueng^[4]	15 g
Tamlueng	ตำลึง	[tām.lɯ̄ŋ]	Tael	4 baht^[4]	60 g
Chang	ชั่ง	[t͡ɕʰâŋ]	Catty	20 tamlueng^[4]	1,200 g
Hap	หาบ	[hàːp]	Picul	50 chang^[4]	60 kg

References

^ Minutes of the 7th General Conference on Weights and Measures, 1927, page 69
^ ^a ^b Giblin, R. W. (2008) [1908]. "Royal Survey Work.". In Wright, Arnold; Breakspear, Oliver T (eds.). Twentieth century impressions of Siam (65.3 MB). London&c: Lloyds Greater Britain Publishing Company. p. 126. Retrieved 28 January 2012. All cadastral plans are plotted, drawn, and printed to a scale of 1 to 4,000....
^ Great Britain. Foreign Office (1847). "1". Treaty of Commerce and Navigation with The United States. Vol. 22. London: James Ridgway and sons, Piccadilly. p. 592. Retrieved 26 January 2020. ...said fathom being computed to contain 78 English or American inches, corresponding to 96 Siamese inches.... {{cite book}}: |work= ignored (help)
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p Royal Institute (2003), พจนานุกรม ฉบับราชบัณฑิตยสถาน พ.ศ. ๒๕๔๒ (Royal Institute Dictionary, BE 2542) (in Thai), Bangkok: Nanmee Books Publications, ISBN 974-9588-04-5, archived from the original on 2012-01-03.

[CGPM14-1] Minutes of the 7th General Conference on Weights and Measures, 1927, page 69

[Giblin-2] Giblin, R. W. (2008) [1908]. "Royal Survey Work.". In Wright, Arnold; Breakspear, Oliver T (eds.). Twentieth century impressions of Siam (65.3 MB). London&c: Lloyds Greater Britain Publishing Company. p. 126. Retrieved 28 January 2012. All cadastral plans are plotted, drawn, and printed to a scale of 1 to 4,000....

[3] Great Britain. Foreign Office (1847). "1". Treaty of Commerce and Navigation with The United States. Vol. 22. London: James Ridgway and sons, Piccadilly. p. 592. Retrieved 26 January 2020. ...said fathom being computed to contain 78 English or American inches, corresponding to 96 Siamese inches.... {{cite book}}: |work= ignored (help)

[RID-4] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p Royal Institute (2003), พจนานุกรม ฉบับราชบัณฑิตยสถาน พ.ศ. ๒๕๔๒ (Royal Institute Dictionary, BE 2542) (in Thai), Bangkok: Nanmee Books Publications, ISBN 974-9588-04-5, archived from the original on 2012-01-03.

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