Why are the inside diameters of some pipe larger than the stated size?

How is OD and ID of pipe measured?

Quote from the video:
Quote from Youtube video: First determine the nominal diameter for pipes with male threads you'll need to measure the outside diameter or OD of the pipe or pipe fitting wrap a string around the pipe.

Is PVC pipe measured inside or outside?

inside diameter

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.

What is the inside diameter of a 1 inch pipe?

1.029 inches

PVC Pipe sizes are different than the size the pipe is called. For example, a 1 inch PVC Pipe is actually 1.315 inches in outside diameter, and 1.029 inches in inside diameter.

What is the inside diameter of 1 1 2 pipe?

Pipe Size Chart