Vietnamese units of measurement
Vietnamese units of measurement are the largely decimal units of measurement traditionally used in Vietnam until metrication. The base unit of length is the thước or xích. 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 for the English mile.
History
Originally, many thước of varying lengths were in use in Vietnam, each used for different purposes. According to Hoàng Phê, the traditional system of units had at least two thước of different lengths before 1890, the thước ta or thước mộc, equal to, and the thước đo vải, equal to. According to historian Nguyễn Đình Đầu, the trường xích and điền xích were both equal to, while according to Phan Thanh Hải, there were three main thước: the thước đo vải, from ; the thước đo đất, at ; and the thước mộc, from.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. On June 2, 1897, Indochinese Governor-General Paul Doumer decreed that all the variations of thước would be unified at one thước ta to, effective January 1, 1898, in Tonkin. Annam retained the old standard for measuring land, so distance and area in Annam were 4.7/4 and 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:| Name in quốc ngữ | Nôm/Chinese 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 | ?/尺 | 40 cm | 10 tấc | 1 m | 10 tấc |
| tấc | ? | 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. Other than for measuring length, the thước is also used for measuring land area.
- According to the UN handbook, some areas unofficially use 1 trượng =. According to Hoàng Phê, the trượng has two definitions: 10 Chinese chi or 4 thước mộc.
- The tấc is also given as túc. According to the UN handbook, some areas unofficially use 1 tấc =.
;chai vai
;dặm
;lý or lí
;sải
Area
The following table lists common units of area in Vietnam in the early 20th century, according to the UN handbook:| Name in quốc ngữ | Chinese/Nôm name | Traditional value | Traditional conversion | Dimensions | Annamite value |
| mẫu | 畝 | m2 | 10 sào | m2 | |
| sào | 巢 | 360 m2 | 10 miếng | 497 m2 | |
| miếng | 36 m2 | 3 ngũ × 3 ngũ | |||
| xích or thước | 尺/? | 24 m2 | 10 tấc | 33 m2 | |
| than | 4 m2 | 1 ngũ × 1 ngũ | |||
| tấc or thốn | ?/寸 | 2.4 m2 | 10 phân | m2 | |
| phân | 0.24 m2 | ||||
| ô or ghế | 0.16 m2 | 10 khấu | 1 thước × 1 thước | ||
| khấu | 0.016 m2 |
Notes:
- Annamite units of area were 2 times those of other areas, due to units of length being 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.
;công or công đất
;dặm vuông
Volume
The following table lists common units of volume in Vietnam in the early 20th century, according to the UN handbook and Thiều Chửu:| Name in quốc ngữ | Chinese/Nôm name | Traditional value | Traditional conversion | Dimensions | Notes |
| hộc | 斛 | 16 m3 | 10 lẻ | 10 ngũ × 1 ngũ × 1 thước | 1 hộc of unhusked rice ≈ 60 L |
| miếng | 14.4 m3 | 3 ngũ × 3 ngũ × 1 thước | For buying and selling land | ||
| lẻ or than | 1.6 m3 | 1 ngũ × 1 ngũ × 1 thước | 1 lẻ of husked rice ≈ 0.1 L | ||
| thưng or thăng | 2 L | sao | |||
| đấu | 1 L | 2 bát = 5 cáp | |||
| bát | 0.5 L | ||||
| cáp | 0.2 L | 100 sao | |||
| sao or nhắm | 抄 | 2 mL | 10 toát | Grain | |
| toát or nhón | 撮 | 0.2 mL | Grain |
Additionally:
- 1 phương of husked rice = 13 thăng or 30 bát in 1804
- 1 vuông of husked rice = 604 gr 50
- 1 phương or vuông or commonly giạ =, though it is sometimes given as 1 phương = ½ hộc or about 30 L
- During French administration, 1 giạ was defined as for husked rice but only for some other goods. It was commonly used for measuring rice and salt.
- 1 túc =
- 1 uyên =
| 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.
;thùng
Weight
The following table lists common units of weight in Vietnam in the early 20th century:| Name in quốc ngữ | Chinese/Nôm name | Traditional value | Traditional conversion | Modern value | Modern conversion |
| tấn | 擯 | 604.5 kg | 10 tạ | 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.
- The cân is also called cân ta to distinguish it from the kilogram.
- The nén is also given in one source as, but this value conflicts with the lạng from the same source at. 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 =
- 1 chỉ =
;binh
- The binh was equivalent to in Annam.
Time
;giờ
Currency
Traditionally, the basic units of Vietnamese currency were quan, 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 to 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 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 coin was worth 3 zinc 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.