Essential PVC Pipe Sizes Chart for DIY Projects

1. Nominal Pipe Size (NPS)

• The nominal pipe size is a standard way to refer to the size of a PVC pipe. It's not the exact inner or outer diameter. For example, in the NPS system, a 1 - inch PVC pipe doesn't have an actual diameter of 1 inch. The nominal size is used mainly for identification and to match pipes with fittings.

• Common nominal sizes for PVC pipes used in DIY projects range from 1/2 - inch to 4 - inch. The 1/2 - inch pipe is often used for small - scale water supply lines such as under - sink connections. A 3/4 - inch pipe is a popular choice for connecting toilets and other larger fixtures. The 1 - inch pipe can be used for main water supply lines in a small building or for some drainage applications.

2. Outer Diameter (OD)

• The outer diameter is an important measurement when it comes to fitting pipes together. In the case of Schedule 40 PVC pipes (a common schedule for DIY), a 1/2 - inch nominal pipe has an outer diameter of about 0.840 inches. A 3/4 - inch nominal pipe has an outer diameter of around 1.050 inches, and a 1 - inch nominal pipe has an outer diameter of approximately 1.315 inches.

• These outer diameters are crucial for selecting the right fittings. For example, when using a coupling to join two pipes, the inner diameter of the coupling must match the outer diameter of the pipes to ensure a proper and leak - proof connection.

3. Inner Diameter (ID)

• The inner diameter affects the flow capacity of the pipe. The inner diameter of a PVC pipe depends on the outer diameter and the wall thickness. For a Schedule 40 PVC pipe, a 1/2 - inch nominal pipe has an inner diameter of about 0.622 inches. A 3/4 - inch nominal pipe has an inner diameter of around 0.824 inches, and a 1 - inch nominal pipe has an inner diameter of approximately 1.049 inches.

• When planning a DIY plumbing project, the inner diameter is important for calculating the flow rate of water or other fluids. The flow rate formula (Q = A×v, where Q is the flow rate, A is the cross - sectional area of the pipe which is related to the inner diameter, and v is the velocity of the fluid) can help you determine if a particular pipe size will provide enough flow for your needs.

4. Wall Thickness

• The wall thickness of PVC pipes varies depending on the schedule. Schedule 40 is a common choice for DIY projects. For a 1/2 - inch nominal Schedule 40 PVC pipe, the wall thickness is about 0.109 inches. For a 3/4 - inch nominal pipe, it's around 0.113 inches, and for a 1 - inch nominal pipe, the wall thickness is approximately 0.133 inches.

• The wall thickness provides the strength to the pipe. Thicker - walled pipes (such as Schedule 80) are used in applications where higher pressure resistance is needed, but for most DIY plumbing and light - duty drainage, Schedule 40 pipes with their moderate wall thickness are sufficient.

5. Standard Lengths

• PVC pipes are usually sold in standard lengths. In DIY projects, you'll often find pipes in 10 - foot lengths. Some suppliers may also carry 5 - foot or 20 - foot lengths. The length of the pipe you choose can affect the number of joints you need to make and the overall cost and complexity of your project.

• For example, if you're running a long water supply line, using longer pipes may reduce the number of couplings and joints, which can potentially reduce the risk of leaks and make installation quicker. However, longer pipes can be more difficult to handle and transport.