PVC Fittings & Parts
The Outside Diameter of the pipe is not the PVC Pipe Size
PVC Pipe sizes are so named by the measurement of the inside diameter (also called the bore) of the PVC pipe, and not the outside diameter. If you measure the outside diameter it will give you a larger reading than the actual PVC Pipe Size. The pipe will always be larger on the outside than the size name, as the thickness of the ‘walls’ of the pipe make it larger.
Correct way to Measure
Reference the Nominal Pipe Size (NPS) naming convention or PVC specifications, which identifies the diameter of the hole of a PVC pipe with a closely-related dimensional number for its size. Therefore the Pipe Size for all of our products is based on the inside hole or ‘bore’ of the PVC pipe that it fits. This is the correct way to measure what PVC Pipe Size you need.
Incorrect way to Measure
You should never use the outside diameter of the pipe to determine your PVC pipe size. If you measure the outside diameter of your PVC pipe and order based off that measurement you will almost always receive the next PVC Size up. Never order PVC products based off the outside diameter.