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
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
20 wa[4] 40 m
Yot โยชน์ [jôːt] Yojana 400 sen[4] 16 km
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)
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
Salueng สลึง [sā.lɯ̌ŋ] 3.75 g
Baht or
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


  1. ^ Minutes of the 7th General Conference on Weights and Measures, 1927, page 69
  2. ^ 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....
  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)
  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.