The breast shield size is the funnel part of your breast shield kit that you place on your breast to express breastmilk from your breast pump. 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 four different breast shield sizes.


The first step to determining your breast shield size is finding out the diameter 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 or outer edge. Based on your measurement, determine your Zomee breast shield size.

 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 centimeters. Make sure the ruler is underneath your nipple 

 3. Multiply the number by 10 ( 1CM = 10MM)

 4. 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 24mm – 28mm, 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 Certified Lactation Consultant can be a helpful resource. Lactation Consultants are clinicians that have received advanced training in assisting breastfeeding moms and babies. 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.