Thai units of measurement

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 1:4,000.¹ 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 script	IPA pronunciation	Meaning equivalent	Relative equivalent	Metric equivalent
Length
Krabiat	กระเบียด	[krā.bìat̚]	Quarter of a finger		0.5208 cm
Nio	นิ้ว	[níw]	Siamese inch² Cf. Digit (unit) finger (unit)	4 krabiat³	2.083 cm
Khuep	คืบ	[kʰɯ̂ːp̚]	Span	12 nio³	25 cm
Sok	ศอก	[sɔ̀ːk̚]	Cubit	2 khuep³	50 cm
Wa	วา	[wāː]	Fathom (outstretched arms)	4 sok³	2 m
Sen	เส้น	[sên]	Cf. Rope (unit) line of rope¹ Chain (unit)	20 wa³	40 m
Yot	โยชน์	[jôːt̚]	Yojana	400 sen³	16 km
Area
Tarang wa	ตารางวา	[tāː.rāːŋ wāː]	Square wa		4 m²
Ngan	งาน	[ŋāːn]	Work	100 tarang wa	400 m²
Rai	ไร่	[râj]	Plantation	4 ngan 1 Square sen	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 mue³	31.25 mL
Fai mue	ฟายมือ	[fāːj mɯ̄ː]	Grain held in the palm	4 kam mue³	125 mL
Thanan	ทะนาน	[tʰā.nāːn]	Coconut shell used for measuring	8 fai mue³	1 L
Thang	ถัง	[tʰǎŋ]	Bucket	20 thanan³	20 L
Sat	สัด	[sàt̚]	Measuring basket	25 thanan³	25 L
Kwian	เกวียน	[kwīan]	Cartload	100 thang³	2 m³
Weight/mass
Salueng	สลึง	[sā.lɯ̌ŋ]			3.75 g
Baht or Bat	บาท	[bàːt̚]	Tical	4 salueng³	15 g
Tamlueng	ตำลึง	[tām.lɯ̄ŋ]	Tael	4 baht³	60 g
Chang	ชั่ง	[t͡ɕʰâŋ]	Catty	20 tamlueng³	1,200 g
Hap	หาบ	[hàːp̚]	Picul	50 chang³	60 kg

References

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)
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.

[Giblin-1] 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....

[2] 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-3] 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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