Breast Pump Basics: Flange Sizing


Breast Pump Basics: Flange Sizing

From the rudimentary suction contraptions of ancient civilisations to the modern mechanical breast pumps we have today, the tools and techniques for expressing breastmilk have come a long way. However, despite these advancements, one aspect has been overlooked time and time again: flange sizing.

In this blog post, we’ll explore the evolution of breast pumps and flange sizing, and discuss why getting the right fit is the key to a comfortable and efficient pumping experience.

The evolution of breast pumps

Archaeological evidence from as far back as the Stone Age tells us that materials such as clay pots, animal skins, and basic suction devices were used to express breast milk. These early contraptions, although crude by today’s standards, served a vital purpose in ensuring infant nourishment when direct breastfeeding was not feasible.

In the early 1900s, inventors like Edward Lasker and Einar Egnell pioneered mechanical breast pumps, laying the groundwork for today’s devices. However, there was one problem: the design of these pumps — particularly the flange or funnel through which the nipple is placed — was based on research from the dairy industry rather than specific human studies.

Fast forward to the present day and thankfully we’ve come a long way in terms of research and design of breast pumps. With the introduction of hands-free pumps such as the Elvie and Momcozy, expressing milk is easier and more comfortable than ever before. There are even some newer pumps in the USA that use a combination of vibration, massage and suction, closely mimicking what a baby does at the breast to make it as efficient as possible.

What is flange sizing and why does it matter?

For years, the standard flange size (the part of the pump that surrounds the nipple) has been 24mm, with some larger options available. However, following lots of clinical research and measuring by IBCLCs such as Jeanette Mesite Frem, we know that very few nipples are 24mm in diameter. We also know that breast size has no relation to nipple size.

This is one of the reasons that a circular ruler has become a must-have tool in any IBCLC’s kitbag. In my private practice, most of the clients I’ve measured fall between 15mm and 19mm, with some outliers of 9mm and 24mm.

Generally both nipples are similar in size but occasionally the left and right are not the same. Some will advise to measure the nipple diameter and increase the flange insert size by 2mm or 4mm. In my experience, the measured diameter with no additions generally works best to achieve the desired outcome: a pain-free experience with good milk flow.

The outdated ‘one size fits all’ approach to flange sizing can lead to pinching, discomfort, nipple damage, and decreased milk removal efficiency — in other words, a very unpleasant pumping experience that might come to an end a lot sooner than you had hoped.

Challenges of researching and choosing a breast pump

In spite of all this research, many pumping manufacturers have been slow to adjust their flange sizes accordingly. Some companies are now offering smaller sizes as accessories, which is definitely a step in the right direction, but many others continue to offer the same pump motor in a different casing or colour, usually with fresh marketing and a significant price hike.

As we all know, navigating the world of breast pumps and accessories can be overwhelming, especially for new parents who are already sleep deprived and adjusting to their new roles. It’s no wonder partners tell me that they run to Tesco at 2am and grab the first breast pump they see!

Additionally, the stigma associated with pumping versus direct breastfeeding can further complicate the decision-making process. With limited information and resources, most new parents will inadvertently select a breast pump with an ill-fitting flange, which can lead to many of the issues outlined above.

The future of flange sizing and pumping support

Breastfeeding and expressing breast milk are deeply personal experiences for mothers, and they deserve all the support and resources available to them. Whether a mother chooses to breastfeed exclusively, pump exclusively, or a combination of both, her decision should be respected and supported.

Flange sizing might seem like a minor aspect of the breastfeeding journey, but getting it right can significantly impact a mother’s comfort, milk supply, and overall pumping experience. Manufacturers should prioritise offering a range of flange sizes to accommodate diverse nipple diameters, rather than adhering to a one-size-fits-all approach.

Healthcare professionals and lactation consultants have a vital role to play too, by providing accessible and accurate information about flange sizing and supporting mothers to make informed choices about their breastfeeding journey.


If you’re struggling to navigate the minefield of breast pumps, you’re not alone!

Come along to my next Pumping Masterclass in April and learn everything you need to know to have a successful pumping experience. At the end of this live online workshop, there will be a Q&A session where you can get all your burning questions answered.

Spaces are limited, so click here to get signed up to the Pumping Masterclass! If you can’t make it to the live workshop, you can purchase the recording separately 🙂

Book Pumping Masterclass Now

Breast Pump Basics: Flange Sizing

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