Tube and Pipe Measurements

Here's how it works

Now a year old, one of our most popular blog posts is about how to measure tube and pipe. To celebrate, we’ve created a travel size version.

The naming convention for both tube and pipe is based on two key measurements: outside diameter and the wall thickness.

Tube is measured and referred to according to its outer diameter and gauge, meaning its wall thickness.

Common gauges include 10, 11, 12, 13, 14, 16, 18 and 20. The lower the gauge, the thicker the wall: 10 gauge tube has a .134 wall thickness, whereas 20 gauge tube has a .035 wall thickness.

A tube that has an outside diameter of 1-1/2 inches and a wall thickness of .035 is called out as “one and a half inch 20 gauge tube”.

Now onto pipe.

Pipe size is specified by the nominal pipe size (NPS) for diameter in inches and a “Schedule” or Sch. for wall thickness.

Pipe has a variety of wall thicknesses, depending on the use. Popular schedules include Sch. 5, 10, 40 and 80.

A pipe that has an O.D. measurement of 1.66 inches and a Schedule of 0.140 inches is “named” or called out as “one and one fourth inch Sch. 40 pipe” in a parts drawing.

In short, tube and pipe are named according to outside diameter and wall thickness, using specific terminology based on the material.

Additional information and charts can be found in our post from October, 2019.