Tech Tip: How to measure oval tubing

Question: What size coupler should I order for my oval tubing?

Answer: Since there are different kinds of ovals, simply adding the length of the cross section and dividing by 2 may not always give you the correct dimension you need. The method we use to measure oval tubing to get the diameter of the coupler will work on any type of round tubing, regardless of its shape. 

To begin, you will need the following:

• Pen or pencil
• Ruler or tape measure
• Paper
• Calculator

First thing we will do is cut a thin strip of paper. For larger diameter tubing, newspaper or butcher paper will work also. We want to be able to wrap the strip around your tubing.

Wrap the strip of paper around the tubing allowing it to overlap slightly. If it does not overlap, use a longer strip of paper or tape multiple strips together to extend it. Draw a straight line across the overlapping part of the strip. 

Lay the strip on a flat surface and measure the distance between the lines that you made. For simplicity, we are using millimeters for our measurements. This measurement will give you the circumference of the tube.

We can then use this equation to solve for the diameter of the tube. d= C/π

The result will give you a pretty accurate dimension for the coupler that you will need for your tube.

BONUS: To convert millimeters to inches, divide the measurement by 25.4