Understanding PEX Pipes Sizes & Dimensions

PEX pipes come in varying sizes and dimensions making them suitable for different applications. In this guide, we will explore some of the common dimensions and sizes.

Let’s dive right in.

What is PEX Pipe?

PEX pipe is a special type of synthetic pipe that is commonly used for plumbing purposes. PEX pipes have numerous advantages over other pipes such as cost-effectiveness, ease of installation, flexibility as well and durability that make them stand out as the best plumbing pipes.

PEX Pipes
PEX Pipes

Common PEX Pipe Sizes

PEX pipes are normally designed in different sizes to suit various plumbing functions. For instance, the commonly known sizes include 1/2-inch, 3/8-inch, 3/4-inch as well as 5/8-inch PEX pipes.

As such, each of these sizes carries a different plumbing function from the other. For example, 3/4-inch size PEX pipes are commonly used in story buildings and large apartments.

On the other hand, 1/2-inch PEX pipes can be applied in both small-scale and higher commercial applications due to their ease of acquisition as well as versatility.

PEX Pipe SizeFunction
  • Used in highly populated areas where there is little space for effective plumbing.
  • Are commonly applied in almost all plumbing purposes for example residential.
  • Applied major industrial projects and storey buildings such as apartments.
4.5/8 inch
  • Applied in large commercial plumbing.
5.1 inch·         Applied in major industrial applications.

PEX Pipe Thickness

PEX pipes can be categorized into two based on their thickness. This includes PEX B and PEX A.


These are special types of PEX pipes manufactured through an industrial process known as the peroxide process.

As compared to other types of PEX pipes, they are poised to be the most preferred PEX pipes due to their flexibility, durability, and resistance to adverse weather conditions.


They are cheaper alternatives for PEX A pipes with a thickness of an inch. As opposed to PEX A pipes, PEX B pipes have a relatively low life span as well as less flexible. It should also be noted that they are manufactured through a process known as the silane process that involves conjoining the pipes.


PEX C pipes are less expensive as compared to PEX B. Similarly, they are less durable and commonly affected by harsh weather conditions such as extreme cold that causes freezing.


As, opposed to other types of PEX pipes, they are the most durable since they have an aluminum coating thus making them the most expensive type of PEX pipe.  Additionally, they are suitable for numerous applications such as in heating systems.

How to Measure PEX Pipe Size

Before measuring the size of a given PEX pipe, it is important to first determine the type of the pipe.  For instance, PEX pipes can come in three different types such as male, female, or no threads. After that, follow the steps highlighted below;

  • Carefully measure the outer diameter of no thread or male pipes and note down the measurements on a piece of paper. Afterward, determine the diameter of the female pipes (inside diameter) using a caliper or a string.
  • Conversion of the measured diameters into required nominal size for example DN (Diameter Nominal) or NPS (Nominal Pipe Size).

Considerations when Calculating PEX Pipe Size

Water Pressure

In applications that require relatively high water pressure such as showers, 1/2-inch PEX pipes are recommendable. This is due to their smaller diameter thus increasing water pressure.


The diameter of PEX pipes refers to the distance across one end of the PEX pipe to another. As such, the diameter of PEX pipes influences various aspects such as installation and pipe fixation.

Length of Pipe Runs

The length of pipe runs is equally important in calculating the PEX size in the sense that it influences the size of the diameter. For instance, short pipe runs would require smaller diameters and vice versa.

PEX Pipes
PEX Pipes

Flow Rate

Various applications require different flow rates thus important to determine the specific flow rate required by a given application before purchasing PEX pipes.


The appropriate PEX pipe for a given application should therefore be easy to install and maintain. Installation may vary depending on the pipe size and dimensions.

Manufacturers’ Guideline Considerations

PEX pipe manufacturers normally provide manual guidelines indicating various applications of various PEX pipe sizes.

Type of Project

Different types of projects require different types of PEX pipes. For instance, large commercial projects prefer 5/8-inch PEX pipes.


As you can see, there are many sizes of PEX pipes designed for different applications. Depending on your unique specifications, ensure you choose the correct diameter and thickness.

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