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Choosing The Right Breast Shield/Flange Size

Why is it important to make sure my breast shield/flange is right for me? 

Comfort and efficiency!  Breast shields come in different (and many) sizes to ensure mummies are able to find the most comfortable fit. A breast shield that is too small will cause nipple pain, whereas a breast shield that is too big may cause pain and inflammation. A good-fitting breast shield is imperative for mummies to make the most out of pumping sessions. 

While most breast pumps come with a default breast shield size, mummies can easily purchase a better-fitting flange or insert. Keep in mind that breast shield sizing can change throughout your breastfeeding journey. You might even find yourself needing different sizes for each breast. At Pupsik, we carry a wide range of breast shields, flanges and inserts for all your pumping needs. 

How to measure?

We recommend measuring your nipple after 5 minutes of pumping on a low setting (using default breast shield size) as the nipple swells during pumping and varies for every woman.

Step 1: Measure your nipple diameter. 

After your nipple is swollen, measure the diameter of your nipple, starting at the base of the nipple. This does NOT include the areola. Tips: Measure in front of a mirror so you can lay your ruler perfectly. 

Step 2: Select a shield size.

After pumping:
Add 2 to 3mm to your measured size .
For example, if your nipple measures 20mm after pumping, u would want to try a 22mm shield. 

Before pumping:
(If you do not have a breast pump yet, try to stimulate your nipple before measuring)


Checking if your breast shield is the proper fit 

Now that it's time to test your new shield, here are signs to look out for to see if it's the right fit! 


  • Flange fits comfortably around your breast
  • Only your nipple and a small part of your areola (or none) enter the tunnel during pumping sessions 
  • Your nipples are able to move freely during pumping sessions without rubbing against the side of the tunnel
  • After pumping, your breasts feel soft and emptied
  • Milk supply remains the same or improves
  • Overall comfortable and free of pain

Every breast is different

While this guideline is a great place to start for finding the right fit, there are other factors which can impact what breast shield size is the right fit for you. To reiterate the point that every breast is different and the nipple size can change throughout your breastfeeding journey. Measurements might be different even throughout the day (you might be fuller in the morning after a few hours without pumping or feeding at night, or smaller in the evening after pumping throughout the whole day). Your measurements might change after milk supply is well-established (approximately 10 weeks postpartum), 

It may take a few trials and errors to get the right one, but it will be worth it when you feel your breast-pumping sessions become more comfortable. 

*Different brands may have different guidelines for selecting the right size. Do follow the guidelines provided by brands if applicable.

Useful tools for measuring your nipple size: