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Correctly Sizing Breast Shields on Pumping Supplies


  • What: Breastshields for pumping
  • Why: Size matters
  • Where: Amazon or your local baby store

Most pumps come with all the accessories that you need to get started. But who knew that the clear plastic breast shields come in a variety of sizes?  I cried for the first six weeks of pumping because I didn’t know more options existed. Find a store or check online for a different size shield compatible with your pump.

Medela has five standard sizes, measured in millimeters: 21mm, 24mm, 27mm, 30mm, and 36mm. Other brands offer additional sizes: 19, 25, 29, and 34. The measurement indicates the diameter of the inside opening of the shield aka the size of your nipple), but all you need to know is whether you want to try a bigger size or smaller. All Medela breastpumps, for example, come with a 24mm shield, so if that’s not working for you, experiment. The cost of extra shields (also known as flanges) is minimal compared to the cost of the pump and can dramatically increase your comfort.

Medela Personal Fit Breast Shield on Amazon

You could need different sizes for each side, or the size you need might change later on in your pumping experience.Sadly, it’s nearly impossible to tell what size you need before delivery and until you actually pump, as the vacuum pressure can cause things to shift.

Not sure if the size is the problem? Here’s some helpful hints: if your nipples are rubbing against the sides of the tunnel, if any part of your breast is turning white or losing its normal color while pumping, or if you feel like you didn’t get all the breastmilk out, try a different size.


Some companies make breastshields in other materials as well. Medela, for example, made them in a softer, squishier type plastic called SoftFit that felt better against my skin than the rigid plastic that comes standard. Sadly, they no longer appear to sell that product, but investigating other options never hurts.

It can make all the difference between suffering through each pumping session and having a non-painful attachment.

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