# Vietnamese units of measurement

Vietnamese units of measurement (Vietnamese: hệ đo lường Việt Nam) are the largely decimal units of measurement traditionally used in Vietnam until metrication. The base unit of length is the thước (chữ Nôm: 𡱩; lit. "ruler") or xích (chữ Hán: 尺). Some of the traditional unit names have been repurposed for metric units, such as thước for the metre, while other traditional names remain in translations of imperial units, such as dặm Anh (English "dặm") for the mile.

## History

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-General Paul 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.

## Length

The following table lists common units of length in Vietnam in the early 20th century, according to a United Nations Statistical Commission handbook:
Early 20th-century units of length :
| Name in chữ Quốc ngữ | Hán/Nôm name | Traditional value | Traditional conversion | Modern value | Modern conversion |
| trượng | 丈 | 4 m | 2 ngũ = 10 thước | | |
| ngũ | 五 | 2 m | 5 thước | | |
| thước or xích | 𡱩/尺 | 40 cm | 10 tấc | 1 m | 10 tấc |
| tấc | 𡬷 | 4 cm | 10 phân | 10 cm | 10 phân |
| phân | 分 | 4 mm | 10 ly | 1 cm | 10 ly |
| ly or li | 釐 | 0.4 mm | 10 hào | 1 mm | |
| hào | 毫 | 0.04 mm | 10 ti | | |
| ti | 絲 | 4 μm | 10 hốt | | |
| hốt | 忽 | 0.4 μm | 10 vi | | |
| vi | 微 | 0.04 μm | | | |
Notes:
* 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).
Miscellaneous units:

### chai vai

    1 chai vai = 14.63 metres (48.0 ft)

### dặm

    According to Hoàng Phê (1988), 1 dặm = 444.44 metres (1,458.1 ft). According to Vĩnh Cao and Nguyễn Phố (2001), 1 dặm = 1 800 xích (Chinese chi) = 576 metres (1,890 ft)

### lý or lí

    According to Vĩnh Cao and Nguyễn Phố (2001), there are two kinds of lý: 1 công lý = 1 km = 3 125 xích, while thị lý is a traditional unit equal to 1 562.55 xích.

### sải
## Area

The following table lists common units of area in Vietnam in the early 20th century, according to the UN handbook:
Early 20th-century units of area :
| Name in chữ Quốc ngữ | Hán/Nôm name | Traditional value | Traditional conversion | Dimensions | Annamite value |
| mẫu | 畝 | 3 600 m$^2$ | 10 sào | | 4 970 m$^2$ |
| sào | 巢 | 360 m$^2$ | 10 miếng | | 497 m$^2$ |
| miếng | | 36 m$^2$ | | 3 ngũ × 3 ngũ | |
| xích or thước | 尺/𡱩 | 24 m$^2$ | 10 tấc | | 33 m$^2$ |
| than | | 4 m$^2$ | | 1 ngũ × 1 ngũ | |
| tấc or thốn | 𡬷/寸 | 2.4 m$^2$ | 10 phân | | 3.313 5 m$^2$ |
| phân | | 0.24 m$^2$ | | | |
| ô or ghế | | 0.16 m$^2$ | 10 khấu | 1 thước × 1 thước | |
| khấu | | 0.016 m$^2$ | | | |
Notes:
* Annamite units of area were (⁠4.7/4⁠)$^2$ times those of other areas, due to units of length (trượng, tấc, etc.) being ⁠4.7/4⁠ times those of other areas, as explained above.
* According to the UN handbook, the phân is also written phấn.
* The sào is also given as cao. Tonkin and Annam had different definitions of the sào.
Miscellaneous units:

### công or công đất

    The công, used for surveying forested areas, typically in southwestern Vietnam, was equivalent to 1,000 square metres (11,000 sq ft).

### dặm vuông

    The dặm vuông measures 1 dặm × 1 dặm.

## Volume

The following table lists common units of volume in Vietnam in the early 20th century, according to the UN handbook and Thiều Chửu:
Early 20th-century units of volume :
| Name in chữ Quốc ngữ | Hán/Nôm name | Traditional value | Traditional conversion | Dimensions | Notes |
| hộc | 斛 | 16 m$^3$ | 10 lẻ | 10 ngũ × 1 ngũ × 1 thước | 1 hộc of unhusked rice ≈ 60 L |
| miếng | | 14.4 m$^3$ | | 3 ngũ × 3 ngũ × 1 thước | For buying and selling land |
| lẻ or than | | 1.6 m$^3$ | | 1 ngũ × 1 ngũ × 1 thước | 1 lẻ of husked rice ≈ 0.1 L |
| thưng or thăng | | 2 L | 1 000 sao | | |
| đấu | | 1 L | 2 bát = 5 cáp | | |
| bát | | 0.5 L | | | |
| cáp | | 0.2 L | 100 sao | | |
| sao or (colloquially) nhắm | 抄 | 2 mL | 10 toát | | Grain |
| toát or (colloquially) nhón | 撮 | 0.2 mL | | | Grain |
Additionally:
* 1 phương of husked rice = 13 thăng or 30 bát (bowls) in 1804
* 1 vuông of husked rice = 604 gr 50
* 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.
* 1 túc = 3+1⁄3 microlitres (0.00020 cu in)
* 1 uyên = 1 litre (0.22 imp gal; 0.26 US gal)
The following table lists units of volume in use during French administration in Cochinchina:
Units of volume in Cochinchina :
| Name in quốc ngữ | Traditional conversion | Traditional value | Usage | Weight |
| hộc | 26 thăng | 71.905 L | unhusked rice | 1 tạ of unhusked rice = 68 kg |
| vuông | 13 thăng | 35.953 L, later 40 L | husked rice | |
| thăng | | 2.766 L | | |
| hiệp | 0.1 thăng | 0.276 L | | |
| thược | 0.01 thăng | 0.0276 L | | |
Notes:
* Unhusked rice was measured in hộc while husked rice was measured in vuông because a hộc of unhusked rice becomes 1 vuông after husking.
* 1 hộc of unhusked rice weighs 1 tạ.
Miscellaneous units:

### thùng

    In Cochinchina and Cambodia, 1 thùng (lit. "bucket") = 20 litres (4.4 imp gal; 5.3 US gal). The thùng is also given as tau.

## Weight

The following table lists common units of weight in Vietnam in the early 20th century:
Early 20th-century units of weight :
| Name in Chữ Quốc ngữ | Hán/Nôm name | Traditional value | Traditional conversion | Modern value | Modern conversion |
| tấn | 擯 | 604.5 kg | 10 tạ | 1 000 kg | 10 tạ |
| quân | | 302.25 kg | 5 tạ | 500 kg | obsolete |
| tạ | 榭 | 60.45 kg | 10 yến | 100 kg | 10 yến |
| bình | | 30.225 kg | 5 yến | 50 kg | obsolete |
| yến | | 6.045 kg | 10 cân | 10 kg | 10 cân |
| cân | 斤 | 604.5 g | 16 lạng | 1 kg | 10 lạng |
| nén | | 378 g | 10 lạng | | |
| lạng | 兩 | 37.8 g | 10 đồng | 100 g | |
| đồng or tiền | 錢 | 3.78 g | 10 phân | | |
| phân | 分 | 0.38 g | 10 ly | | |
| ly or li | 厘 | 37.8 mg | 10 hào | | |
| hào | 毫 | 3.8 mg | 10 ti | | |
| ti | 絲 | 0.4 mg | 10 hốt | | |
| hốt | 忽 | 0.04 mg | 10 vi | | |
| vi | 微 | 0.004 mg | | | |
Notes:
* 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)
Miscellaneous units:

### binh

* The binh was equivalent to 69 pounds (31 kg) in Annam.

## Time
### canh (更)

    The canh or trống canh is equal to 2 hours (7,200 s).

### giờ

    The giờ, giờ đồng hồ, or tiếng đồng hồ is equal to 1 hour (3,600 s).

## Currency

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 Northern and Southern dynasties 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.