# Is Exhaust Pipe Measured Inside Or Outside?

The outer diameter of an exhaust pipe is measured in inches. While the Nominal Pipe Size defines the outer diameter of the pipe, there is additional information available about the pipe. So it’s only a matter of room on the inside.

The majority of exhaust pipes will be measured in terms of OD measurements, which are the pipe’s outside dimensions, also known as its outer diameter. That implies that if you were to acquire a three-inch pipe, such as the one we have here, the outside diameter of the pipe would be three inches instead of three inches and a half.

## Why do exhaust tips and mufflers use internal diameter?

Exhaust tips and mufflers, for the most part, are measured in terms of internal diameter since they are designed to glide over the exhaust pipe. The majority of exhaust pipe is measured in terms of external diameter.

## How do you find the outside diameter of a pipe?

The first step is to measure the pipe’s circumference with a tailor’s measuring tape (or a piece of string you can then measure with a standard measuring tape or ruler). Then double the circumference by p (3.14), which gives you the outer diameter of the circle.

## What size should the exhaust pipe be between exhaust manifold and muffler?

For example, the tubing between the exhaust manifold and the muffler may be 2.5 inches in diameter at first, but it might be increased to 3 inches for the tailpipe. Keep in mind to measure both the inlet sizes (the portion facing towards your engine) and the exit sizes while you’re taking your measurements! Taking your measures? (the section pointing towards your tailpipe).