Thailand adopted the metric system on 17 December 1923.
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. 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 | Siamese inch Cf. Digit (unit) finger (unit) |
4 krabiat | 2.083 cm | |
| Khuep | คืบ | Span | 12 nio | 25 cm | |
| Sok | ศอก | Cubit | 2 khuep | 50 cm | |
| Wa | วา | Fathom (outstretched arms) |
4 sok | 2 m | |
| Sen | เส้น | Cf. Rope (unit) line of rope |
20 wa | 40 m | |
| Yot | โยชน์ | Yojana | 400 sen | 16 km | |
| Area | |||||
| Tarang wa | ตารางวา | Square wa | 4 m | ||
| Ngan | งาน | 100 tarang wa | 400 m | ||
| Rai | ไร่ | 4 ngan | 1,600 m (16 a) | ||
| Volume | |||||
| Yip mue | หยิบมือ | Pinch | 7.8125 mL | ||
| Kam mue | กำมือ | Grain held in an enclosed hand | 4 yip mue | 31.25 mL | |
| Fai mue | ฟายมือ | Grain held in the palm | 4 kam mue | 125 mL | |
| Thanan | ทะนาน | Coconut shell used for measuring | 8 fai mue | 1 L | |
| Thang | ถัง | Bucket | 20 thanan | 20 L | |
| Sat | สัด | Measuring basket | 25 thanan | 25 L | |
| Kwian | เกวียน | Cartload | 100 thang | 2 m | |
| Weight/mass | |||||
| Salueng | สลึง | 3.75 g | |||
| Baht or Bat |
บาท | 4 salueng | 15 g | ||
| Tamlueng | ตำลึง | Tael | 4 baht | 60 g | |
| Chang | ชั่ง | Catty | 20 tamlueng | 1,200 g | |
| Hap | หาบ | Picul | 50 chang | 60 kg | |
References
- Minutes of the 7th General Conference on Weights and Measures, 1927, page 69
- ^ Giblin, R. W. (2008) . "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.
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