Fitting your breast pump

fitting your flange size on your breast pump graphic

Fitting your breast pump

Using the correct breast flange or shield size while pumping is not only important for comfort but also for efficiency. Using the incorrect flange size can result in discomfort, pain, nipple damage and not being able to maximise your milk output using your breast pump.

The following information will help you choose the right size breast shield for your needs.

What is a Breast Pump Flange?

The Flange is the funnel shaped part of the breast pump that is placed around the nipple while pumping. The flange forms a vacuum seal around the areola allowing the nipple to be drawn into the tunnel of the pump so the milk can be extracted.

medela personalfit flex breast shield side view

Medela PersonalFit Flex Breast Shield for Solo Single and Swing Maxi Double Breast Pumps.

Why Mums love the Medela PersonalFit  Flex Breast Shield

  • Available in 4 sizes – 21mm – 30 mm,
  • Fits Medela Solo Single and Swing Maxi Double Breast Pumps,
  • Adapts to your shape,
  • 360° rotation,
  • 105° angle ensures better milk flow,
  • Adjustable fit for extra comfort,
  • BPA free!

Flange sizing

Breast pumps generally come with the standard size breast shield that is 24mm. Most brands offer additional sizing that you can purchase separately if the standard size is not right for you.

Common flange sizes range from 19mm through to 36mm. For nipple sizes that are smaller than flange sizes available with pumps, you may need to purchase an insert that fits inside the flange to reduce its size.


Measure your nipple size when you are purchasing your pump so you can order extra flange sizes and save delivery time and costs later.

Finding the right fitting Flange

Fitting the flange size to your nipple size will assist the pump to work efficiently and ensure your pumping experience is more comfortable. The nipple diameter is the most important part to get the fit correct.

Measuring your nipple size

To determine the size of your nipple:

  1. Ensure the nipple is perked/stimulated to replicate the size of your nipple when pumping
  2. Determine the diameter of your nipple by measuring from the nipple base to the top of the nipple (image provided below)
  3. When you have determined your nipple size, select the flange/breast shield size that is 3-4mm larger than your nipple size. For example, if your nipple size is 21mm, a 24mm flange is the ideal size for you.
  4. Be sure to measure both of your breasts in case you need two different sizes.
fitting your flange size on your breast pump graphic

Image courtesy of The Night Owl

Easy nipple measuring tool

It can be tricky to accurately measure your nipple with a tape measure or ruler, because, well, your nipple is not flat! To make it easier to measure your nipple quickly and easily, we have created a tool for you to use.

Enter your details below to have the template sent to your inbox.

Nipple Size Template Iinstructions for use:

  1. Ensure you set the page size to A4 for printing to ensure accurate scale.
  2. To check that the sizing is correct, measure the 1cm square to ensure it measures exactly 1cm. If the measurement is incorrect you will need to adjust the printing size until the 1cm gauge is correct.
  3. Fold the paper along the fold line of the row/s you need to use.
  4. Cut around the half circle line to form a hole in the paper.
  5. Use the circle guides to determine your nipple size. Doing this in front of the mirror may help.
  6. Select your flange size that is 3-4mm larger than your nipple size for a good fit.

Why we love the Medela Freestyle Hands Free Breast Pump

  • Trusted breast pump manufacturer for over 60 years!
  • Discreet pumping
  • Lightweight and comfortable to wear
  • Include 21mm and 24mm flange sizes
  • 2-Phase Expression mimics baby’s sucking rhythm
mum wearing medela hands free breast pump

The Medela Freestyle Hands Free Breast Pump takes pumping to new level! 

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