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Pipe | Stormwater Pipe | PVC Fittings | Plumbing Supplies

How to measure pipe size


Whether you will be using PVC stormwater pipe, galvanised pipe, garden hose or a poly pipe, determining the correct pipe size for your project is important. This will also assist you to get the right plumbing supplies and plumbing fittings to get your job done.

So how do you measure your pipe size?

Most people assume pipe size is the outer diameter of the pipe - but the pipe size actually refers to the "nominal diameter".

The easiest way to find what pipe size you need is to follow the steps below and use the conversion table below

For Male threads

Pipe Size | Male Thread | Plumbing Fittings

1. As shown in the picture above, measure the circumference (outer diameter) of your pipe or pipe fitting by using the below steps

    • Wrap a string around the pipe
    • Mark the point where the string touches together
    • Use a ruler or measuring tape to find the length between the tip of the string and the mark you made (circumference)
    • Divide the circumference by 3.14159

      2. Use the Pipe Size table below to find the corresponding pipe size

      For Female Threads

      Pipe Size | Female Thread | Plumbing Fittings

      1. Measure the inner diameter of your pipe or pipe fitting. You can use a ruler or tape measure to find the distance between the two points as shown in the above diagram

      2. Use the Pipe Size table below to find the corresponding pipe size

      Pipe Size Table

       Outer or Inner diameter (cms)

       Pipe Size                 (inches)

      0.795 cms 1/16"
      1.03 cms 1/8"
      1.37 cms 1/4"
      1.71 cms 3/8"
      2.13 cms 1/2"
      2.67 cms 3/4"
      3.34 cms 1"
      4.21 cms 1 1/4"
      4.82 cms 1 1/2"
      6.03 cms 2"
      7.30 cms 2 1/2"
      8.89 cms 3
      10.16 cms 3 1/2"
      11.43 cms 4"


      We hope you find above table useful to determine the size of your pipe and/or pipe fitting.

      Plumbers Best provides Australian Standard plumbing supplies such as

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