In North America, the measurements of PVC pipe are indicated by two different numbers. The first number is the schedule, which indicates the thickness of the pipe wall. The second is the nominal pipe size (NPS), which indicates the diameter.

Identification

PVC pipe comes in sizes ranging from 1/8 inch to 16 inches. The thickness of the pipe wall will vary depending on the schedule of the pipe. The two schedules associated with PVC pipe in the USA are Schedule 40 and Schedule 80.

Types - Schedule 40

There are 16 different NPS diameters listed for PVC pipe on Schedule 40. These diameters (in inches) are 1/2, 3/4, 1, 1-1/4, 1-1/2, 2, 2-1/2, 3, 4, 5, 6, 8, 10, 12, 14 and 16. The actual measurements will not be exactly as indicated by the NPS number. For example, the outside diameter of a one-inch Schedule 40 PVC pipe measures 1.315 inches. The inside diameter measures 1.049 inches.

Types - Schedule 80

The available diameters of Schedule 80 PVC pipe (in inches) are 1/2, 3/4, 1, 1-1/4, 1-1/2, 2, 2-1/2, 3, 4, 5, 6, 8, 10, 12, 14 and 16. Again, these NPS measurements do not correspond exactly with the width of the pipe. A one-inch Schedule 80 PVC pipe has an outside diameter of 1.315 inches and an inside diameter of 0.957 inches. Consult Schedules 40 and 80 for exact dimensions of each NPS size.