Units of length , 长度单位 , cháng dù dān wèi 。
mm , 毫米 , háo mǐ 。
cm , 厘米 , lí mǐ 。
dm , 分米 , fēn mǐ 。
m , 米 , mǐ 。
km , 千米 , qiān mǐ 。
km , 公里 , gōng lǐ 。
inch , 英寸 , yīng cùn 。
feet , 英尺 , yīng chǐ 。
长度单位是指丈量空间距离上的基本单元，是人类为了规范长度而制定的基本单位。其国际单位是“米”（符号“m”），常用单位有毫米（mm）、厘米（cm）、分米（dm）、千米（km）、米（m）、微米（μm）、纳米（nm）等等。长度单位在各个领域都有重要的作用。
The unit of length refers to the basic unit for measuring the spatial distance, and is the basic unit formulated by humans to regulate the length. Its international unit is “meter” (symbol “m”), common units are millimeter (mm), centimeter (cm), decimeter (dm), kilometer (km), meter (m), micrometer (μm), nanometer (Nm) Wait. The unit of length plays an important role in various fields.
理解长度单位，首先要理解它的上位概念——单位。《现代汉语词典》对“单位”的解释是：计量事物的标准量的名称。在测量中，以同类量的某定量为基准量，测定已知量相当于基准量的多少倍，该基准量称为单位。如厘米是计量长度的单位，克是计量质量的单位，秒是计量时间的单位。作为数学的例子，还可以说1是自然数的单位，分子为1的分数是分数的单位。
To understand the unit of length, we must first understand its upper concept-unit. The interpretation of “unit” in “Modern Chinese Dictionary” is: the name of the standard quantity for measuring things. In the measurement, a certain quantitative of the same quantity is used as the reference quantity to determine how many times the known quantity is equivalent to the reference quantity, and the reference quantity is called the unit. For example, the centimeter is the unit of measuring length, the gram is the unit of measuring mass, and the second is the unit of measuring time. As an example of mathematics, it can also be said that 1 is the unit of natural numbers, and the fraction whose numerator is 1 is the unit of fraction.
在测量线段的长度时，需要选定某一线段作为测量标准，并规定其长度为1，称这条线段为长度单位。长度单位有很多，主单位是米，其余都是派生的单位。测量时，根据实际需要选择合适的长度单位。如测量跑道的长度用米作单位，测量两个城市之间的距离用千米作单位，而测量跳远的距离用厘米作单位，等等。
When measuring the length of a line segment, a certain line segment needs to be selected as the measurement standard, and its length is specified as 1, and this line segment is called the unit of length. There are many length units, the main unit is meters, and the rest are derived units. When measuring, select the appropriate length unit according to actual needs. For example, the length of the runway is measured in meters, the distance between two cities is measured in kilometers, and the distance of long jumps is measured in centimeters, and so on.
中国传统的长度单位有里、丈、尺、寸、寻、仞、扶、咫、跬、步、常、矢、筵、几、轨、雉、毫、厘、分，等。其基本换算关系如下：
1丈=10尺；1尺=10寸；1寸=10分；1分=10厘；
1丈≈3.33米；1尺≈3.33分米；1寸≈3.33厘米；
1千米(km)=1000米；1米(m)=100厘米；1厘米(cm)=10毫米；
1里=150丈=500米；2里=1公里(1000米)。