How to Measure Exhaust Pipe Diameter

Exhaust upgrades are one of the most popular performance modifications in the automotive world.

Like regular maintenance, it’s common for many drivers to perform their own exhaust work, but to do that you’ll need to know a few key measurements to ensure that all of the exhaust system’s components fit together.

Chief among these is measuring exhaust pipe diameter. Read on to learn how to find it.

The Two Measurements You Need to Know

Exhaust modifications can add some serious horsepower to your car, in some cases up to 10%, and can increase your vehicle’s fuel efficiency. When you’re installing new exhaust components, you’ll need two measurements: the inner and outer diameters of the exhaust pipe.

The inner diameter is the measurement of the interior of your exhaust pipe excluding the edges, while the outer diameter includes the pipe’s edges.

Both measurements are important. If you’re installing a new muffler or exhaust tips, you’ll need to know the inner diameter. Those components fit inside the pipe.

On the other hand, the pipes that compose your exhaust system are concerned with the outer diameter, as they slide inside your muffler or exhaust tips.

Measuring the Outer Diameter

Measuring your exhaust pipe’s outer diameter is simple if the end of the pipe is exposed. You’ll just take a tape measure, lay it across the pipe, and measure from the outer edge of one side of the pipe to the outer edge of the other side.

Things are a little more complicated if your pipe is covered by an exhaust tip or inside of a muffler. If this is the case for you, you’ll need to have a pair of dial calipers or do a simple geometry equation.

Calipers will take the measurement for you. Just open the calipers and place them around the exhaust pipe. Then, slowly close them until they’re in contact with the pipe. The calipers will display the measurement.

If you don’t have calipers, you’ll need to calculate the exhaust pipe diameter. First, measure the pipe’s circumference, or the distance around the pipe. Then you’ll divide that by 3.14. That basic formula gives you the diameter.

Measuring the Inner Diameter

Like measuring the outer diameter, measuring the inner diameter is simple if the end of the pipe isn’t blocked. You’ll place your tape measure across the end of the pipe and take your measurement. This time, you’ll exclude the edges of the pipe.

If you can’t get to the end of the pipe, you’ll have to remove whatever is blocking access to it or cut a section of the pipe.

Knowing Your Exhaust Pipe Diameter Is Important

If you want to perform exhaust upgrades on your ride, you’ll need to know both the inner and outer diameter of your exhaust pipe. Fortunately, figuring out these measurements is relatively easy. With a tape measure, a little bit of math, and a handy pair of calipers, you’ll find your car’s exhaust pipe diameter.

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