PVC, or polyvinyl chloride, pipes are soft plastic pipes commonly used in a variety of plumbing applications. They are readily available at most hardware stores in an array of sizes. The size of a PVC pipe is closest to the pipe's inside diameter (ID). The ID of a pipe varies, however, based on the wall thickness, or schedule, of the pipe, making the size little more than a reference tool. PVC pipes are commonly available in schedules 40, 80, and 120.
Schedule 40 Pipe Sizes
Schedule 40 pipes are the thinnest PVC pipes available, meaning that they have the biggest inside diameter. They are available as small as 1/8 inch or as large as 24 inches. They are sized in fractions of an inch until the size surpasses 4 inches, at which point they are sized by the inch. The wall thickness of schedule 40 pipes ranges from 0.156 inches for 1/8-inch pipe to 1.456 inches for the 24-inch pipe. The schedule 40 pipe sizes are:
1/8, 1/4, 3/8, 1/2, 3/4, 1, 1 1/4, 1 1/2, 2, 2 1/2, 3, 3 1/2, 4, 5, 6, 8, 10, 12, 14, 16, 18, 20, 22, and 24 inches.
Schedule 80 Pipe Sizes
Schedule 80 pipes are thicker than schedule 40s, allowing for more heavy-duty applications with higher pressure flowing through them. They are available in the same sizes as the schedule 40 pipes, and have the same outside diameter (OD). The ID is smaller because the pipe walls are thicker. Schedule 80 pipe walls vary from 0.210 inch thick for 1/8-inch pipe to 2.582 inches for 24-inch pipe.
Schedule 120 Pipe Sizes
Schedule 120 pipes are the thickest commonly available PVC pipes and are available in fewer sizes than the schedule 40 or 80 pipes. These pipes allow for the most pressure out of the three. They are available from 1/2 inch to 8 inches. The wall thickness varies from 0.360 inch to 1.436 inches. The schedule 120 pipe sizes are:
1/2, 3/4, 1, 1 1/4, 1 1/2, 2, 2 1/2, 3, 4, 6, and 8 inches.