PVC 101 - About PVC Sizes | PVC Fitting Dimensions

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PVC Pipe Measuring Methods

For those who prefer a direct approach without diving into the comprehensive details of PVC pipe measurement, you can see the most common ways to measure PVC pipe and find the right size for your project. Below, we've outlined four straightforward methods. These methods not only assist you in identifying the size of the PVC pipe you might already have but also in determining the size you might require for future projects or repairs:

1

Download our PVC Size Guide

You can download our easy-to-use PVC Size Guide, a print-to-scale solution that lets you physically compare your PVC pipe to each PVC pipe size.

Download PVC Size Guide

2

Read the PVC Pipe Markings

Every plumbing-grade manufacturer marks their pipes differently; however, you can view the PVC Pipe Markings page to learn how to read them.

How to Read Pipe Markings

3

Compare PVC Pipe to Objects

View our Pipe Size Comparison chart, which will give you an idea of how each PVC Pipe Size diameter equates to everyday household objects.

View Pipe Comparison Chart

4

Verify PVC Size by Dimensions

You can view our PVC Pipe Dimensions chart and physically measure your pipe up against actual PVC pipe dimensions for each size to help locate your size.

PVC Size Dimensions Chart

1

Don't measure the pipe outside diameter.

The outside diameter (OD) is not used to find the PVC pipe size; instead, the inside diameter (ID) of the pipe is used, measuring between the inside edges.

Learn more about OD

2

PVC schedule is important for some products.

PVC Schedule refers to the thickness of the PVC pipe wall. This thickness can become important when using internal fit products and accessories.

Learn More about Pipe Schedule

3

Not all types of pipe and tube are compatible.

Some pipes are designed for specific applications, such as water or sewer lines. Make sure you choose the right type of PVC pipe for your project.

Learn More about Compatability

1. The OD is not the PVC Pipe Size.

PVC pipe sizes are named using the Nominal Pipe Size (NPS) system, which helps us understand how big the pipe is inside. For example, if a pipe has markings that show it as 3/4", the inside diameter (ID) is roughly 3/4 inches. Similarly, a pipe labeled as 1" has an ID of about 1 inch.

Understanding the distinction between the size of the pipe (like 3/4" or 1") and the outside diameter (OD) is crucial. The OD is always larger than the size name due to the thickness of the pipe walls. For example, a 3/4" PVC pipe actually has an OD of about 1.050 inches, and a 1" PVC pipe has an OD of approximately 1.315 inches.

To find the size of a PVC pipe, it's always best to measure the inside diameter (ID) using a measuring tape or a ruler. If you only have the pipe's OD, you can use the PVC Pipe Dimensions table to determine the size based on its actual measurements.

The correct way to Measure

PVC pipe follows the Nominal Pipe Size (NPS) naming convention, which identifies the diameter of the hole of a PVC pipe with a closely related dimensional number for its size. Therefore, the Pipe Size for all FORMUFIT products uses the inside diameter or ‘bore’ of the PVC pipe that it fits. This method is the correct way to measure the PVC pipe size you need.

The incorrect way to Measure

You should never use the outside diameter of the pipe to determine your PVC pipe size unless you are using a reference chart. If you measure the outside diameter of your PVC pipe and order based on that measurement, you will almost always receive the next PVC size up. Never order PVC products based on the outside diameter unless you are referencing a PVC pipe dimensions chart.

PVC Pipe Size Dimensions Chart

3. Not all pipe is compatible.

It's important to remember that not all types of pipe are compatible with FORMUFIT fittings and accessories. This incompatibility is because PVC pipes are measured using the inner diameter, while most other types of pipes, tubes, and rods are sized and measured based on the outer diameter. Other issues include non-compatible physical properties, such as difficulty connecting plastic to other materials such as wood or metal.

CTS/CPVC Pipe

The most commonly confused non-compatible pipe is Copper Tube Size (CTS) plastic pipe, also known as CPVC which uses an entirely different sizing system. For more information on CPVC, please see our CPVC Incompatibilities Page for more information.

CPVC Incompatibilities Page

ABS Pipe

While ABS pipe is size-compatible with most FORMUFIT products, it must use a unique transitional cement or the pipe-to-fitting connection must be screwed together for a secure connection. ABS pipe is also not recommended as a structural pipe as it is very brittle and easily broken.

Polypropylene Pipe

Polypropylene pipe, or poly pipe, is commonly used for sprinklers and irrigation systems. It is flexible yet fragile and matches Schedule 40/80 dimensions. However, it connects loosely and is designed for compression or barbed connectors, not slip fittings. It is incompatible with PVC cements and cannot be fusion welded.

Acrylic Tube/Rod

When it comes to plastic-based materials, acrylic tubes and rods may seem similar to PVC fittings and accessories at first glance. However, it's important to note that these two materials are not dimensionally compatible, as acrylic tubes are measured based on their outer diameter.

Steel Conduit/Pipe

Some steel pipes share the same outside diameters as corresponding PVC pipe sizes and are size-compatible, but there is no way to connect the steel pipe to the plastic PVC fitting. Metal EMT conduit uses a separate measurement system and will not fit PVC fittings or accessories.

Wooden Dowels

Wooden dowels won't work with PVC fittings as they use a different measurement system. Dowels are measured by their outer diameter, which does not align with the sizing used in PVC. This mismatch means that wooden dowels won't fit securely in PVC fittings, leading to poor connections.