Si (length)
Chinese unit of length
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Si (simplified Chinese: 丝; traditional Chinese: 絲; pinyin: sī) is a traditional Chinese unit of length. One si is equal to 1/10 of a hao, 1/100 000 of a chi, or 3+1⁄3 μm. In the field of engineering, one si equals 10 μm.[1][2]
Present law on Chinese length units
This law of length measurement was issued by the Chinese government in 1929, and has been effective since 1 January 1930. The base unit chi is defined to be 1/3 meter.[3][4][5]
| Pinyin | Character | Relative value | Metric value | Imperial value | Notes |
|---|---|---|---|---|---|
| sī | 絲 (T) or 丝 (S) | 1⁄100 000 | 3+1⁄3 μm | 0.000131 in | |
| háo | 毫 | 1⁄10 000 | 33+1⁄3 μm | 0.00131 in | Chinese mil |
| lí | 釐 (T) or 厘 (S) | 1⁄1000 | 1⁄3 mm | 0.0131 in | Chinese calibre |
| fēn | 市分 | 1⁄100 | 3+1⁄3 mm | 0.1312 in | Chinese line |
| cùn | 市寸 | 1⁄10 | 3+1⁄3 cm | 1.312 in | Chinese inch |
| chǐ | 市尺 | 1 | 33+1⁄3 cm | 13.12 in | Chinese foot |
| zhàng | 市丈 | 10 | 3+1⁄3 m | 3.645 yd | Chinese yard |
| yǐn | 引 | 100 | 33+1⁄3 m | 36.45 yd | Chinese chain |
| lǐ | 市里 | 1500 | 500 m | 546.8 yd | Chinese mile. |
Metric length units
These units are based on the metric system. The Chinese word for metre is 米 mǐ, which can take the Chinese standard SI prefixes (for "kilo-", "centi-", etc.). In the engineering field, traditional units are rounded up to metric units.[6][7]
| Pinyin | Character | Relative value | Metric value | Imperial value | Notes |
|---|---|---|---|---|---|
| hū | 忽 | 1⁄1000000 | 1 μm | Authorized name: 微米 | |
| sī | 絲 (T) or 丝 (S) | 1⁄100000 | 10 μm | Authorized name: 忽米 | |
| háo | 毫 | 1⁄10000 | 100 μm | Authorized name: 絲米 (T) or 丝米 (S) | |
| lí | 釐 (T) or 厘 (S) | 1⁄1000 | 1 mm | Authorized name: 毫米 | |
| fēn | 公分 | 1⁄100 | 10 mm | Authorized name: 釐米(T) or 厘米(S) | |
| cùn | 公寸 | 1⁄10 | 100 mm | Authorized name: 分米 | |
| chǐ | 公尺 | 1 | 1 m | Authorized name: 米 | |
| Zhàng | 公丈 | 10 | 10 m | Authorized name: 十米 | |
| yǐn | 公引 | 100 | 100 m | Authorized name: 百米 | |
| lǐ | 公里 | 1000 | 1000 m | this li is not the small li above, which has a different character and tone |