Inside diameter of 4 inch pvc pipe

Relationship between the outer diameter and inner diameter of 4-inch PVC pipes

PVC pipe sizes are usually marked with the outer diameter (OD, Outer Diameter), while the inner diameter (ID, Inner Diameter) is calculated based on the outer diameter and the wall thickness of the pipe. The outer diameter of a 4-inch PVC pipe is usually 4 inches (101.6 mm), and the inner diameter varies depending on the wall thickness of the pipe.

The inner diameter of a 4-inch PVC pipe is usually between 3.48 inches (about 88.5 mm) and 3.50 inches (about 89 mm). This difference depends on the wall thickness of the pipe, especially pipes of different pressure grades. Specifically, common PVC pipes such as Schedule 40 and Schedule 80 have different wall thicknesses, which leads to changes in the inner diameter.