Everything You Didn’t Know About Flange Sizing - and Why It Matters

For new moms navigating the world of breastfeeding and pumping, it can feel like every answer brings five more questions. And one topic that often flies under the radar (until it causes pain, frustration, or dwindling milk supply) - is flange sizing.

“I was pumping eight times a day and barely getting 10 ounces total,” says Morgan, a new mom from Yucaipa, CA. “I thought my supply was low. I didn’t realize my flanges were actually choking my nipples.”

It wasn’t until Morgan booked a full pumping consult at Inland Breastfeeding Center that she discovered she’d been using a size 24mm - nearly double what her actual nipple needed!

“We see this all the time,” explains Karolina Ochoa, BSN, IBCLC, CD, a Board Certified Lactation Consultant and Certified Doula with over 10 years of experience. “Most pumps come with standard sizes, 24mm or 27mm, but those sizes fit almost no one correctly.”

And it’s not just about size. The shape, material, and even the texture of the flange can make a huge difference.

Not All Flanges Are Created Equal

Some parents find matte plastic works better. Others need a more flexible silicone tunnel. For those with elastic nipples - a common condition where the nipple stretches far into the flange - going smaller is often better, not bigger.

“It’s a myth that your nipple should move freely without touching the tunnel walls,” Karolina shares. “Some friction is actually okay. What we want to avoid is your areola getting pulled in, that causes severe damage over time.”

Your Size Can Change - And Probably Will!

Just like shoes might feel tighter or looser depending on the season (or pregnancy), your nipple size and sensitivity can shift during your lactation journey.

“You might need one size at one week postpartum and a completely different one two months later,” Karolina says. “We always recommend remeasuring and reassessing any time something feels off.”

One golden rule? Pumping should feel either like nothing at all, or like a gentle tug. “If you're bracing yourself when you turn the pump on, that's a red flag,” she adds.

Another Game Changer

Lubrication. So many parents don’t realize that dry pumping can cause micro-tears, irritation, and even reduce milk output. That’s why we always recommend using a safe, nipple-friendly pumping spray - and we have a favorite! Our go-to organic coconut oil-based pumping spray is made right here in the USA, packed with clean, nourishing ingredients you can trust. It glides on effortlessly, reduces friction, and helps make every session more comfortable. You can grab a bottle at your next visit to Inland Breastfeeding Center, or order it online here.

The Science and the Strategy

At Inland Breastfeeding Center, pumping appointments go beyond “pick a number and hope for the best.” Clients get personalized measurements, they can try different shapes and textures, and even learn how to spot signs of inefficient emptying or tissue damage.

“Within two days of changing my flange size, my clogged ducts cleared and my output jumped from 1oz to 3oz per session,” says Becca, a Riverside mom of a preemie baby. “I was ready to give up before that.”

And while TikTok is full of DIY measuring tools and advice, experts caution against going it alone for too long. “There’s a reason we need to see you, either in person or via telehealth” Karolina notes. “We assess not just measurements, but nipple elasticity, breast shape, and how the pump is working overall. It’s a whole-body, whole-system approach.”

The Bottom Line? Don’t Suffer in Silence

If pumping hurts, your output is low, or something just doesn’t feel right, don’t chalk it up to failure. “Your body is not broken,” says Karolina. “You probably just need a better-fitting flange.”

At Inland Breastfeeding Center, our lactation consultants are trained in advanced flange sizing and pumping optimization. We offer full pumping appointments to help you find the best flange for your unique anatomy - because pumping shouldn’t hurt, and you deserve support that actually works.

Think your flange might not be the right fit? Schedule a full pumping consult in person or via Telehealth at Inland Breastfeeding Center today and let’s take the guesswork out of your journey.