There are two main units of measurement for length in the world today. One is the metric system, which includes meters (m), centimeters (cm), millimeters (mm), etc. It is commonly used in Southeast Asia such as Europe, China, and Japan. The other is the imperial system, which mainly uses inches as the unit of measurement, which is equivalent to the market size of China's old system. It is more commonly used in European and American countries such as the United States and the United Kingdom.
1. Metric measurement: (base 10)
1m =100 cm=1000 mm
1cm=10mm
2. Imperial measurement: (octal)
1 inch=25.4 mm=8 inches, for example: 3/8 π x 25.4=9.52mm
Subdivision units for inches:
0 1/8 1/4 3/8 1/2 5/8 3/4 7/8 1 inch
1/16 3/16 5/16 7/16 9/16 11/16 13/16 15/16
1/32 3/32 5/32 7/32 9/32 11/32 13/32 ……
1/64 3/64 5/64 7/64 9/64 11/64 13/64 ……
3. Products with a diameter of less than 1/4 inch are represented by a designation, such as:
4#， 5#， 6#， 7#， 8#， 10#， 12#