How a Pipe Diameter Tape Measure Gives You the Average Diameter of a Pipe

What is the “average” diameter of a pipe? This term would come into play only if the pipe is not exactly round in cross section.

A Flattened Pipe, in the Shape of an Oval
A Flattened Pipe, in the Shape of an Oval

If the pipe were deformed and flattened out, what would be the diameter of it? It would have a long diameter and short diameter. So how would you determine its original diameter?

Instead of using a caliper or micrometer and doing

An Irregular Deformation of a Pipe, in Cross Section
An Irregular Deformation of a Pipe, in Cross Section

some kind of calculation, you can do it the easy way. Use a pipe diameter tape measure. It will easily tell you what the original, or average, diameter is. Just wrap it around the pipe, and read off the “original” or “average” outside diameter.