Breast shields or flanges are the part of the pump that goes directly on the breast. They are essential for pumping efficiency so that you can get the most out of your sessions. Incorrectly sized breast shields can lead to soreness, blocked milk ducts, and impact milk production. One size does not fit all, that is why Zomee offers you a wide range of breast shield sizes.


The first step to determining your breast shield size is finding out the diameter of the base of your nipple. Using the ruler in your manual, measure the diameter of your nipple at the base (across the middle) in millimeters (mm). Do not include the areola. Based on your measurement, add 2-3 millimeters for your Zomee breast shield size. Tip - if your nipple measures 16mm in diameter, your recommended breast shield size is 19mm.

3 Simple Steps: 

1. Stimulate your nipple so it perks up

2. Use a ruler to measure the diameter of your nipple (as shown in the picture) in millimeters

3. Follow the selection guide table


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

Using the breast shield size you have chosen, center your nipple and gently hold the breast shield against your breast. 

Note: Please keep in mind that no two breasts are identical. Many pumpers use a different size breast shield on each side. Your size may also change throughout the course of your breastfeeding journey.


The standard breast shield sizes are between 21mm – 24mm, but you may need a smaller or larger size. It is important to confirm you have chosen the correct size, and a good way to check is by testing the two breast shield sizes that were included with your pump (or the size chosen after measuring your nipples).

Here is how to check:

-Hold the shield against your breast, making sure your nipple is centered in the tunnel.

-During pumping your nipple should be able to move freely in the breast shield tunnel, not rubbing against the sides. There will be space around your nipple and only a small part of the areola is drawn into the tunnel.

-After pumping breasts feel emptied.

The breast shield you are using is:

Too small if some or your entire nipple rubs against the sides of the breast shield funnel. Too big if your areola is drawn into the breast shield funnel and/or rubbing up against the sides of the breast shield funnel.

*Please note that pressing the breast shields too hard against your breasts when pumping can block your milk ducts.


Breast shield size is essential to creating proper suction so that expression of your breastmilk can occur. If pumping is painful or uncomfortable and this is affecting your milk supply, reaching out to a Lactation Professional or Care Provider can be a helpful resource. They can diagnose and treat many lactation issues, as well as guide you to finding your way in your breastfeeding journey.

We offer individualized virtual lactation consulting support to our Zomee moms, free of cost. Click here to schedule a consultation.