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Choose Your Breast Shield Size

 Why Choosing the Right Shield Size is Important?

Breast shields are sometimes also called flanges. While comfort is often the driving determinant in figuring out the right size, using the correct sized breast shield will also make your pumping more efficient. Pumping can be hard enough on its own but having an unfitting shield may impact the amount of milk you are able to pump. It’s good to keep in mind that the right breast shield size may change over the course of your pumping and nursing journey, so it’s a good idea to check occasionally you are still using the right size. Or you might find that your breasts need different shield sizes – that’s normal too. Remember, pumping shouldn’t hurt!

The starting point for choosing the correct breast shield is to determine your optimal size based on your nipple diameter.

 Suggested size
Up to 17mm
17mm - 20mm
20mm - 25mm

Getting your sizing right

Since your breast shield size is also dependent on breast tissue and skin elasticity, it’s important to confirm you’ve chosen the correct size. Here’s how to check:

  • Using the 24 mm breast shields included with your pump (or the size chosen after measuring your nipples), centre your nipple and gently hold the breast shield against your breast.
  • Adjust your breast pump’s vacuum through stimulation all the way up to a slightly uncomfortable vacuum, and then down one notch.
  • When your breast shield fits correctly, your nipple will be centered in the breast shield tunnel and will move freely during pumping


It’s worth resizing the shield if you struggle with the following:

  • Your nipple is rubbing the sides of the breast shield tunnel to the point of causing discomfort.
  • You see excessive areola being pulled into the breast shield tunnel.
  • You have redness on or at the base of the nipple during and/or after pumping.
  • Your nipples or areola are turning white during and/or after pumping.
  • Your breasts still feel full after pumping.

Note: Pressing the shields too hard against your breasts when pumping can block your milk ducts.

Shop Breast Shields here (available in sizes 21mm, 24mm, and 27mm) or the Complete Breast Pump Spare Set here.