Originally, many thước of varying lengths were in use in Vietnam, each used for different purposes. According to Hoàng Phê (1988), the traditional system of units had at least two thước of different lengths before 1890, the thước ta (lit. "our ruler") or thước mộc ("wooden ruler"), equal to 0.425 metres (1 ft 4.7 in), and the thước đo vải ("ruler for measuring cloth"), equal to 0.645 metres (2 ft 1.4 in). According to historian Nguyễn Đình Đầu, the trường xích and điền xích were both equal to 0.4664 metres (1 ft 6.36 in), while according to Phan Thanh Hải, there were three main thước: the thước đo vải, from 0.6 to 0.65 metres (2 ft 0 in to 2 ft 2 in); the thước đo đất ("ruler for measuring land"), at 0.47 metres (1 ft 7 in); and the thước mộc, from 0.28 to 0.5 metres (11 in to 1 ft 8 in).
With French colonization, Cochinchina converted to the metric system, the French standard, while Annam and Tonkin continued to use a thước đo đất or điền xích equal to 0.47 metres (1 ft 7 in). On June 2, 1897, Indochinese Governor-GeneralPaul Doumer decreed that all the variations of thước (such as thước ta, thước mộc, and điền xích) would be unified at one thước ta to 0.40 metres (1 ft 4 in), effective January 1, 1898, in Tonkin. Annam retained the old standard for measuring land, so distance and area (such as sào) in Annam were 4.7/4 and (4.7/4)2 times the equivalent units in Tonkin, respectively.
The thước is also called thước ta to distinguish it from the metre (thước tây, lit. "Western ruler"). Other than for measuring length, the thước is also used for measuring land area (see below).
According to the UN handbook, some areas unofficially use 1 trượng = 4.7 metres (15 ft). According to Hoàng Phê (1988), the trượng has two definitions: 10 Chinese chi (about 3.33 m) or 4 thước mộc (about 1.70 m).
The tấc is also given as túc. According to the UN handbook, some areas unofficially use 1 tấc = 4.7 centimetres (1.9 in).
1 phương or vuông or commonly giạ = 38.5 litres (8.5 imp gal; 10.2 US gal), though it is sometimes given as 1 phương = ½ hộc or about 30 L
During French administration, 1 giạ was defined as 40 litres (8.8 imp gal; 11 US gal) for husked rice but only 20 litres (4.4 imp gal; 5.3 US gal) for some other goods. It was commonly used for measuring rice and salt.
The tấn in the context of ship capacity is equal to 2.8317 or 1.1327 cubic metres (100.00 or 40.00 cu ft).
The cân (lit. "scale") is also called cân ta ("our scale") to distinguish it from the kilogram (cân tây, "Western scale").
The nén is also given in one source as 375 grams (13.2 oz), but this value conflicts with the lạng from the same source at 37.8 grams (1.33 oz). The 375-gram value is consistent with the system of units for measuring precious metals.
The đồng is also called đồng cân, to distinguish it from monetary uses.
The French colonial administration defined some additional units for use in trade: nén = 2 thoi = 10 đính = 10 lượng
Units for measuring precious metals:
The lạng, also called cây or lượng, is equal to 10 chỉ. 1 cây = 37.50 grams (1.323 oz)
1 chỉ = 3.75 grams (0.132 oz)
The binh was equivalent to 69 pounds (31 kg) in Annam.
The canh or trống canh is equal to 2 hours (7,200 s).
The giờ, giờ đồng hồ, or tiếng đồng hồ is equal to 1 hour (3,600 s).
Traditionally, the basic units of Vietnamese currency were quan (貫, quán), tiền, and đồng. One quan was 10 tiền, and one tiền was between 50 and 100 đồng, depending on the time period.
From the reign of Emperor Trần Thái Tông onward, 1 tiền was 69 đồng in ordinary commercial transactions but 1 tiền was 70 đồng for official transactions.
From the reign of Emperor Lê Lợi, 1 tiền was decreed to be 50 đồng.
During the Southern and Northern Dynasties of Vietnam period, beginning in 1528, coins were reduced from 24 millimetres (0.94 in) to 23 millimetres (0.91 in) in diameter and diluted with zinc and iron. The smaller coinage was called tiền gián or sử tiền, in contrast to the larger tiền quý (literally, "valuable cash") or cổ tiền. One quan tiền quý was equivalent to 600 đồng, while 1 quan tiền gián was only 360 đồng.
During the Later Lê Dynasty, 1 tiền was 60 đồng; therefore, 600 đồng was 1 quan.
During the Yuan Dynasty, Vietnamese traders at the border with China used the rate 1 tiền to 67 đồng.
Zinc coins began to appear in Dai Viet during the 18th century. One copper (đồng) coin was worth 3 zinc (kẽm) coins.
Beginning with the reign of Emperor Gia Long, both copper and zinc coins were in use. Originally the two coins had equal value, but eventually a copper coin rose to double the worth of a zinc coin, then triple, then sixfold, until the reign of Emperor Thành Thái, it was worth ten times a zinc coin.
Under French colonial rule, Vietnam used the units hào, xu, chinh, and cắc. After independence, Vietnam used đồng, hào, and xu, with 1 đồng equaling 10 hào or 100 xu. After the Vietnam War, chronic inflation caused both subdivisions to fall out of use, leaving đồng as the only unit of currency. However, Overseas Vietnamese communities continue to use hào and xu to refer to the tenth and hundredth denominations, respectively, of a foreign currency, such as xu for the American cent.
^Hoàng Phê, ed. (1988). Từ điển tiếng Việt (in Vietnamese). Sociology Publishing House.
^Lê Thành Khôi (2000). "Tìm hiểu một số đơn vị đo lường ngày trước" [Understanding some of the units of measurements from the past]. Kỷ yếu Hội thảo phục hồi điện Cần Chánh (in Vietnamese). Huế and Tokyo: Hue Monuments Conservation Center and Waseda University.
^Nguyễn Đình Đầu (1997). Nghiên cứu địa bạ triều Nguyễn – Thừa Thiên (in Vietnamese). Ho Chi Minh City Publishing House.
^Nguyễn Đình Đầu (1994). Nghiên cứu địa bạ triều Nguyễn – Biên Hòa (in Vietnamese). Ho Chi Minh City Publishing House.
^Dương Kinh Quốc (1999). Việt Nam: những sự kiện lịch sử [Vietnam: historic events] (in Vietnamese). Hanoi: Education Publishing House. p. 236.
^ abcdef"World Weights and Measures". Handbook for Statisticians. Statistical Papers. M (1 ed.). New York: Department of Economic and Social Affairs, Statistical Office of the United Nations. 1966. ST/STAT/SER.M/21/rev.1.