Finding the right fit is always important – whether it’s for clothing, shoes or even your breast pump flange size. Soreness, pinching, irritation, and clogged milk ducts don’t sound fun but are all things that can occur if you don’t have the correct flange size. A breast pump flange (breast pump shield) size that is too small or too big could seriously hinder your breast pumping journey. So, be sure to choose the correct size to properly express milk for your infant.

Finding The Correct Breast Pump Flange Size

First, What Is A Breast Pump Flange?

A breast pump flange is the funnel or cone-shaped plastic cup that fits directly over your nipple to form a seal around the areola to create a vacuum that gently draws the nipple into the funnel for milk extraction.

Not having the correct flange size could impact your milk flow by causing blocked milk ducts, pain, nipple damage, swelling, or cuts on the nipple. But with finding the correct size, you can comfortably maximize milk production.

Finding Your Perfect Fit

Motif’s goal is to help mom have the most comfortable pumping journey possible. Our handy flange sizing chart helps you determine your best fit. Be sure to review each size option to choose the one that will fit best.

Finding the right breast pump flange size

To determine what size you need, you’ll need to know your nipple size. You can measure your nipple by taking a ruler or measuring tape to measure the diameter of your nipple (the horizontal width across it). Measure the nipple alone, do not include the areola which is the outer edge around your nipple.

The measurement should be in millimeters (1 cm = 10mm)

Then select your flange size based on your measurement.

breast shield measurments

  • If you measured up to 17mm you’ll fit in a 21mm flange.
  • If you measure up to 22mm use size 24mm.
  • If you measured up to 23mm select size 27mm.
  • If you measured up to 26mm use 30mm.
  • If you measured up to 32 mm use size 36 mm.

You’ll know if you have the right pump shield if:

right fit breast pump flange

  • Your nipple is in the center of the flange and moves freely into the tunnel of the breast pump for comfortable milk expression.
  • Your areola has little to no tissues inside the tunnel of the breast pump.
  • You do not feel areas of the breast that still contain milk, as this could indicate uneven breast milk extraction.
  • You don’t experience any nipple pain.
  • Your nipple and areola do not turn white or become discolored, meaning the blood supply has not been cut off.

Ashley Georgakopoulos, Motif Medical Lactation Director (IBCLC), explained that when looking for the correct fit to, “Find what is comfortable. Too much friction to the tissue, tightness, or painful sucking could indicate the incorrect size. The top of the nipple and its base should be the only part entering the flange tunnel.”

How To Tell If Your Flange Is Too Small

flange size that is too small

If your breast pump flange is too small you may experience:

  • Rubbing as the nipple is pulled against the sides of the breast pump tunnel.
  • Pinching and squeezing of the nipple.
  • Your nipple or areola becomes white or discolored.
  • Low breast milk production.
  • Painful milk extraction.

How To Tell If Your Flange Is Too Big

breast shield too large

If your breast pump flange is too big you may experience:

  • Your areola could become pulled into the flange and tunnel
  • Painful nipple pinching, pulling, and squeezing
  • Lower breast milk production
  • Your nipple or areola could become white or discolored

Bonus Flange Size Tips Pumping with the correct breast pump flange size

  • If this is your first-time breast pumping, consult with a lactation consultant to assist with determining the flange fit according to nipple shape, areola density, and areola fullness.
  • Measure both of your nipples in case they are different sizes. Some moms need two different flange sizes.   
  • Your flange size could change over time, especially after giving birth. Regularly measure your nipples to see if you need to change sizes or not.

All content published on the Motif Medical site is created for informational purposes only. This information should not substitute as medical advice, diagnosis, or treatment. Always consult your doctor or qualified health professional with any questions regarding the health of you or your baby.

Shop New Breastshields