Medela Breastshield Sizing Guide [NEW!]

May 14, 2015

Having properly fitted breastshields isn’t just a matter of comfort, it’s important for pumping efficiency too. Using breastshields that are too large or too small can significantly reduce the amount of milk you can pump and cause unnecessary discomfort, which is why choosing the PersonalFit breastshield size that’s right for you is key to pumping success. Been pumping for a while now? Don’t stop reading. Your breastshield size could change over the duration of your breastfeeding journey, so even if you’ve been pumping for several months, it’s possible that you may benefit from a different size.

Understanding Medela’s PersonalFit Sizing

Pumping should not hurt, ever. For maximum comfort and pumping efficiency, Medela offers five different breastshield sizes that are compatible with all Medela breastpumps:

  • 21 mm
  • 24 mm (the size included with all Medela breastpump kits)
  • 27 mm
  • 30 mm
  • 36 mm

24 mm is our most standard size based on data we receive from our healthcare experts. You may need a different size based on your anatomy or other factors, such as needing a different size per breast or the point you’re at in your breastfeeding journey. As their breasts adapt over the course of lactation, some moms may find that they need a larger size breastshield, while other may benefit from a smaller size.

In order to find your optimal size, you can measure your nipple diameter:

  1. Using a ruler or measuring tape, measure the diameter your nipple at the base (across the middle) in millimeters (mm). 1 cm = 10 mm. Do not include your areola.
  2. Based on your measurement, use the guide below to determine your PersonalFit breastshield size.

PersonalFit breastshield guide MedelaSo, for example: If your nipple measures 16 mm in diameter, your recommended PersonalFit breastshield size is 21 mm because the 21 mm shield fits nipples up to 17 mm in diameter. If your nipple diameter measures 24 mm, your recommended size would be 30 mm.

A note about nipples:

Be sure to understand the difference between your nipple and areola. Your areola is the darkened area on your breast around your nipple. Your nipple is the projection of your mammary gland from which milk is produced.

Medela Nipple Anatomy

Testing Your Breastshield Size

To confirm which size breastshield is the best fit, you should watch the nipple movement during pumping. Your breastshield size also depends on your breast tissue and skin elasticity (not just nipple size alone). In order to determine if your PersonalFit breastshield is the right size, you can perform a quick test using your pump and the breastshields that came with it.

  1. Start with the 24 mm breastshields that were included with your pump (or the size determined by measuring your nipples).
  2. Center your nipple and gently hold the breastshield against your breast. Be careful to not press breastshields too hard against your breasts when pumping – this can block your milk ducts!
  3. Adjust your pump’s vacuum for your Maximum Comfort Vacuum* to achieve optimum suction level, turning the vacuum up until slightly uncomfortable and then down a notch. (*Maximum Comfort Vacuum refers to the highest but still comfortable vacuum setting while pumping. Pumping at Maximum Comfort Vacuum increases pumping efficiency.)
  4. Refer to the below images while pumping:

Medela Breastshield Fit GuideToo Small

If your breastshield is too small, your nipple will rub along the side of the tunnel. Try a larger size.

Too Large

If your breastshield is too large, your nipple, along with excessive areola, will be pulled into the tunnel. You may benefit from a smaller size.

Correct Fit

When your breastshields fit correctly, your nipple will be centered in the breastshield tunnel and move freely during pumping.

Should You Try a New Size?

If you’re wondering whether your breastshields are the right size for your nipples, ask yourself the following questions:

  • Does your nipple rub the sides of the tunnel to the point of causing discomfort?
  • Do you see excessive areola being pulled into the tunnel?
  • Do you see any redness on or at the base of the nipple during and/or after pumping?
  • Is your nipple or areola turning white during and/or after pumping?
  • Do your breasts still feel full after pumping?

If you answered “YES” to any of these questions, we suggest you consider trying a new size by following the measuring instructions above. If you’re still not sure if you selected the right size, please reach out to a lactation consultant or breastfeeding specialist. You can also contact Medela Customer Service at 1-800-435-8316.

Click here to download the breastshield sizing handout [PDF]

Find Medela products in a store near you.

Select your pump to purchase spare parts directly from our website.

Or, visit one of our online retail partners.

Still have questions? We’re hosting a live chat with Lactation Consultant Irene Zoppi on the Medela Facebook page on Monday, May 18th at 8pm (CT). Click here to learn more and RSVP!

129 thoughts on “Medela Breastshield Sizing Guide [NEW!]

  1. Is it just one side of the base and across the nipple or is it base, across nipple, and down the other side of the base? It’s my second kid, and I have horrible baby brain!

    • Hi Susan – Congrats on your growing family! Measure the diameter your nipple at the base (across the middle) in millimeters (mm). 1 cm = 10 mm. Do not include your areola. We hope this helps!

  2. Thank you so much for posting this. WIsh it was here when I needed it years ago. I just sent it to another mom in need. This is invaluable!

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