Primer on Tube, Pipe, and Hose Sizes
Sizing of pipe, tube and hose can seem confusing, but once you know a few things, it will take the mystery out of how to read the sizes and it is easy enough you can do it too!
The first thing you need to know is how the sizes are designated.
Pipe and hose are always measured on the inside diameter of the opening. For example, a 1/2 inch nipple has an opening of 1/2 inch, but the outer diameter is close to 3/4 of an inch.
Tubing is always measured from the outside diameter. The thickness of the tubing can vary, but the outside will be the same. For example, 1/2 x .065 tubing has an OD of .0500 inch, with an inside diameter of .370 because of the thickness of the tube wall.
The next thing to know is most tube and hose are designated in 1/16th of an inch increments. For example, size 4 hose is 1/4 of an inch, 1/16th x 4 = 4/16 or 1/4 inch. Size 6 = 6/16 or 3/8 of an inch, and so on. Below is a list of common sizes. These sizes are used in hydraulics, AN hoses, various pneumatics, and automotive applications.
- Size 3 = 3/16 Inch
- Size 4 = 1/4 Inch
- Size 5 = 5/16 Inch
- Size 6 = 3/8 Inch
- Size 8 = 1/2 Inch
- Size 10 = 5/8 inch
- Size 12 = 3/4 Inch
- Size 16 = 1 Inch
- Size 20 = 1-1/4 Inch
- Size 24 = 1-1/2 Inch
- Size 32 = 2 Inch