How to Measure Pex Pipe Size

Are you looking for an easy way to accurately measure the size of your PEX pipe? We understand that knowing how much pipe you need and what size it should be is crucial when completing any home plumbing project.

How to Measure Pex Pipe Size

That’s why we wanted to give you the knowledge needed to quickly, easily, and consistently measure PEX pipes like a pro. In this guide, we’ll teach you just about how to measure pex pipe size, from reading common data charts to using calipers – tired of wasting time with guesswork? Let’s get started!

Why May You Want to Measure Pex Pipe Size?

1 . To Know the Right Size to Buy

When purchasing Pex pipes for your plumbing needs, it is important to know the right size that will fit your specific project. Measuring the pipe size beforehand will save you time and money by ensuring that you purchase the correct size.

2 . To Determine Water Flow Rate

The diameter of a Pex pipe affects its water flow rate. By measuring the size of your Pex pipe, you can calculate its water flow rate and determine if it is suitable for your needs.

3 . To Plan Your Plumbing System

Knowing the exact measurements of your Pex pipes will help in planning out your plumbing system effectively. This includes determining the layout, connecting different pipes, and estimating the amount of materials needed. Accurate measurements are crucial for a successful plumbing project.

4 . To Identify Potential Issues

If you notice any fluctuations in water pressure or irregularities in your plumbing system, measuring the Pex pipe size can help identify potential issues. A smaller than recommended pipe size may cause low water flow, while a larger one may lead to excessive noise and vibration.

Measuring the Pex Pipe Size Can Help

How to Measure Pex Pipe Size in 5 Easy Steps

Step 1: Gather the Necessary Tools

Before you begin measuring the Pex pipe size, make sure you have all the necessary tools on hand. You will need a tape measure, a permanent marker, and a pair of scissors or utility knife.

Step 2: Determine the Type of Pex Pipe

Pex pipes come in three different types: A, B, and C. Type A is the most common and has a red color, while type B is blue and type C is white. It’s important to know the type of Pex pipe you have as it will affect the measurement process.

Step 3: Measure the Outside Diameter

Using your tape measure, measure the outside diameter of the Pex pipe. This is the distance across the widest point of the pipe.

Step 4: Calculate the Size

Next, you will need to use a simple formula to determine the size of your Pex pipe. Multiply the outside diameter by 3 and then divide that number by 2. For example, if your outside diameter is 1 inch, your calculation would be (1 x 3) /  2 = 1.5 inches. This will give you the size of your Pex pipe.

Step 5: Mark and Cut

Using a permanent marker, make a mark on the Pex pipe where you need to cut it based on your calculated size. Then, use a pair of scissors or a utility knife to make a clean cut at the marked spot. Also, make sure to properly deburr the edge of the cut for a smooth finish.

Using a Permanent Marker

Additional Tips

1 . Do Not Ignore the Diameter

When measuring Pex pipe size, it’s important to pay attention to the diameter of the pipe. This is because different diameters will have different flow rates and pressure capabilities. So, always check the specifications of your project to ensure that you are using pipes with the correct diameter for optimal performance.

2 . Use a Measuring Tape or Ruler

When measuring Pex pipe size, it’s best to use a measuring tape or ruler for accuracy. This will allow you to get precise measurements and avoid any potential errors that may occur from using other tools.

3 . Consider the Type of Pex Pipe

There are three main types of Pex pipes: PEX-A, PEX-B, and PEX-C. Each type has a different measurement system, so it’s important to be familiar with the type of pipe you are using. For example, PEX-A and PEX-B use different measurement systems based on metric measurements, while PEX-C uses a standard naming system for sizes.

4 . Take Note of any Fittings

When measuring Pex pipe size, don’t forget to take into account any fittings that will be used with the pipe. These fittings will affect the overall length of the pipe, so it’s important to consider them in your measurements.

5 . Double Check Your Measurements

Before cutting or installing Pex pipes, it’s always a good idea to double-check your measurements. This will help avoid any potential mistakes and ensure that you have the correct size for your project.

6 . Seek Professional Help if Unsure

If you are unsure about how to properly measure Pex pipe size, it’s always best to seek professional help. A plumber or experienced contractor can provide guidance and assistance in selecting the right size for your project and ensure that everything is installed correctly. Don’t be afraid to ask for help if needed – it’s better to be safe than sorry in the long run. 

Best to Seek Professional Help

Overall, measuring Pex pipe size may seem like a simple task, but paying attention to these additional tips can make a big difference in ensuring that your project is successful and efficient.

So, remember to take note of the diameter, use appropriate measuring tools, consider the type of Pex pipe you are using, factor in any fittings, double-check your measurements, and seek professional help if needed. With these tips in mind, you can confidently measure Pex pipe size and tackle any project with ease.

Frequently Asked Questions

What Precautions Should I Take When Measuring Pex Pipe Size?

When measuring Pex pipe size, it is important to take the following precautions:

  • Use a tape measure or ruler with clear and precise measurements. Avoid using makeshift measuring tools as they may not provide accurate readings.
  • Make sure to measure from the end of one fitting to the end of another fitting, rather than just measuring the length of pipe in between. This will give you a more accurate measurement of the total length needed.
  • Take into consideration any curves or bends in the Pex pipe, as they may affect the overall measurement needed.
  • If possible, use a caliper to measure the outside diameter of the Pex pipe. This is especially important if you are trying to determine the size of a Pex pipe that already has fittings attached.
  • Keep in mind that Pex pipe sizes are typically measured in nominal or inside diameters, rather than outer diameters. Make sure to double check which measurement is being used when determining the size of your Pex pipe.

Can I Use a Regular Tape Measure to Measure Pex Pipe Size?

Yes, you can use a regular tape measure or ruler to measure Pex pipe size. However, it is important to make sure that the measuring tool has clear and precise markings in order to get an accurate measurement. It may also be helpful to have someone assist you in holding the tape measure steady while taking the measurement.

Use a Regular Tape Measure

How Do I Determine the Correct Size of Pex Pipe for my Project?

To determine the correct size of Pex pipe for your project, you will need to consider a few factors such as:

  • The water pressure needed for your specific project.
  • The distance between the water source and where the Pex pipe will be used.
  • The type of fittings that will be used with the Pex pipe.
  • The temperature and flow rate of the water that will be running through the Pex pipe.

It is also recommended to consult a professional plumber or refer to industry guidelines and standards for determining the appropriate size of Pex pipe for your specific project.

How Much Extra Pex Pipe Should I Purchase?

It is always a good idea to purchase some extra Pex pipe for your project, just in case of any unforeseen circumstances or mistakes. It is recommended to purchase an additional 10% of the total length needed for your project.

Can I Cut and Join Pex Pipe to Adjust Size if Needed?

Yes, you can cut and join Pex pipe to adjust the size if needed. However, it is important to use proper tools and methods for cutting and joining Pex pipe to ensure a secure and leak-free connection. It is also recommended to consult a professional plumber or refer to manufacturer guidelines before attempting any modifications on your Pex pipe.  Overall, measuring Pex pipe size accurately is crucial in ensuring the success and efficiency of your project.

Taking the necessary precautions and using appropriate tools and methods will help you achieve the desired outcome. It is always best to consult a professional plumber for any specific questions or concerns regarding Pex pipe size measurement.  Remember, accurate measurements lead to successful plumbing projects!  So take your time, double check your measurements, and be confident in your Pex pipe size before beginning your project.


After learning how to measure pex pipe size, you should now be well-equipped to measure it accurately with your own two hands. It may take some practice to get used to the process of finding it correctly, but with patience and the right tools, anyone can become a master at measuring pex pipe sizes.

So take the knowledge you have gained from this blog post and get your DIY skills on – you’ll impress yourself with how quickly you become an expert pexer! What are you waiting for? Get out there and start measuring that pipe!

Photo of author

Terry Alexander

Hi, I am Terry. I started my professional life as a handyman and did a lot of external and internal repair of home and plumbing support. From my childhood, my passion for home repair and fixtures created an opportuinity to pursue a career in HVAC and plumbing industry. As I gained years of knowledge and my love for plumbing grew overtime, I thought to document my journey so that I could help others who ran into daily problems in their home repair. Hopefully it will help you fix those pesky home repair and plumbing problems that always seem to happen at the worst time possible!

Leave a Comment