The Complete Guide to Measuring Flange Size – BabyBuddha Products
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The Complete Guide to Measuring Flange Size
by Team BabyBuddha
Did you know that, after three months, less than half of new mothers continue to breastfeed their babies? The reasons why vary, but most mothers become concerned about their milk production and ability to breastfeed effectively. This is where breast bumps come into play.

However, using a breast pump isn’t often as intuitive as it might seem. Namely, you need to ensure you’re using the right flange size. Are you a new mom trying to figure out the best size flange for your breast pump? You're not alone!

Choosing a breast pump flange size can be overwhelming, especially if it's your first time. Don't worry, though — we've created this complete guide to help you learn how to measure flange size to find the perfect fit.

Read on to discover all the ins and outs of finding the right flange fit for both you and your little one!

What Is Flange Size?

Let’s take a step back for a second. What’s a flange? A breast pump flange is a curved piece that fits directly over the breast and forms a suction seal between the breast and breast shield to maximize milk flow. 

Breast pump flange size refers to the diameter of that piece of plastic. It's important to get breast pump flanges that fit comfortably on your breast or you won't be able to get an adequate suction vacuum to effectively express milk. 

Not only that, but the right size ensures minimal leakage of breast milk during pumping. Likewise, if you don’t have the right size, you might find the breast pump feels uncomfortable or even painful. This shouldn’t ever be the case!

Understanding Different Flange Sizes

Breast pump flanges range in sizes from 21mm to 36mm, with most breast pumps coming in multiple sizes. 

If you're unsure what size breast pump flange is right for you it could be beneficial to speak with a lactation consultant who can help guide you toward the best size for your breasts. Or, simply keep scrolling and we’ll help you learn how to measure yourself for flange sizing.

At BabyBuddha, we offer four main flange sizes. Explore each sizing below to familiarize yourself with the options before learning how to properly measure your nipples for flange size (and why it’s so important in the first place).


First things first. Your flange size should be about 4mm larger than the diameter of your nipple. You'll need to keep this in mind when measuring your nipples to find the right flanges for breast pumps. Likewise, it means that if your nipples measure between 17mm to 20mm, a 21mm flange size will likely be the perfect fit for you.


According to our research, the average flange size for most women is between 24mm to about 27 to 28mm. This makes our 24mm flange size quite popular (it's why our BabyBuddha Complete Kit comes with two 24mm flanges).

If you measure the diameter of your nipples and they measure between 21 to 24mm then the 24mm flange size should be right for you. However, if you find that your nipples measure right at 24mm then you might want to move up to the 28mm flange.


This breast pump flange size is ideal for those with nipples measuring between 25mm to 28mm. Remember, the flange size should be about 4mm larger than the diameter of your nipple, but ultimately you'll want to find a size that feels comfortable for you. The last thing you want (or need) is pain from breast pumping.


Finally, we offer a 32mm flange as part of our standard flange kits. This size is often suitable for those with nipple diameters between about 28mm to 32mm. With that said, if you need a different size, please don't hesitate to reach out to our team. We'll work with you to provide you with the correct size you need to pump comfortably.

Why Finding the Right Flange Size Is Important

As a new mom, it can be overwhelming to learn all the things you need to do to breastfeed successfully. One of the most important steps is choosing a breast pump flange size that will fit your breast and prevent any breast discomfort while pumping.

A breast pump flange that is too large or too small can cause pain and can affect milk production, so it’s important to find the right size for you. Here are three great reasons why it's important to take some time out to measure your breasts to find the right flange size.

Improve Comfort

Finding the perfect fit for your body is everyone's quest, but when it comes to motherhood, finding the right-sized breast pump flange improves comfort even further. Every mom deserves a comfortable pumping experience ⁠— after all, if you aren’t as comfortable as possible then how can your precious nursing relationship benefit?

Take control of your pumping journey and make sure that you select the best size for your breasts. This ensures that when it's time to start pumping, not only will you be ready to conquer the task with ease, but also with a wonderful sense of comfort too.

Optimize Pump Performance

Getting the right flange size when using a breast pump optimizes pumping performance in more ways than one! Not only is it more comfortable and reduces discomfort, but it can also help regulate how much milk you’re able to express.

If your flange size is too small for your nipples, milk production and flow will be low; if it’s too big, that could result in pain and soreness. As any exhausted new mother knows, this can only add to the frustration of life as a new mom to a hungry baby you're very eager to feed.

Pump More Efficiently

Finally, choosing an optimum flange size when pumping milk makes all the difference in comfort and efficiency. Nobody wants to spend more time pumping than necessary.

An ill-fitting flange size can cause pain during pumping or reduce the effectiveness of your pumping session, so measuring and choosing the right flange is essential for efficiency as you try to fit pumping breast milk into your daily schedule.

Common Issues With Flange Size

The two common issues we see women struggling with when it comes to flange sizing is that the flange is either too small or too large. While it might not seem like a big deal, either one of these issues could cause discomfort or even health issues that'll make it more difficult to pump or breastfeed effectively.

Too Small

Having a flange size that's too small for your breast pump is a headache of galactic proportions. Not only will it leave you greatly uncomfortable, but it could also potentially lead to not being able to express milk completely and efficiently, resulting in a less fulfilling breastfeeding experience.

Even worse, due to the flange being too small, your nipples may become sore and cracked, making the feeling after pumping anything but enjoyable. So if your flange size isn't fitting right, remeasure your nipples and try a different size. If you're still noticing discomfort but feel you have the right size, it might be time to contact a lactation Consultant.

Too Large

You may have heard the old saying "bigger is better," but when it comes to flange size on a breast pump, that adage couldn't be further from the truth! Having too large of a flange size can be painful and cause discomfort because of the extra pressure exerted by the flanges.

In some cases, women experience damage to their nipples due to indentations created by ill-fitted flanges. Furthermore, using flanges that are too big won't let your body form a good seal, so you won't be able to express milk efficiently. So next time you're shopping for flanges for your breast pump, opt for one that's just right for your specific needs.

If you're not sure what size to choose based on the diameter of your nipples then keep scrolling to learn...

How to Measure Flange Size

The flange sizing process may sound like a difficult task, but it's quite easy. All you need is a ruler or measuring tape. You'll take the measuring tape and measure the diameter of your nipple.

However, be sure not to include your areola. You can measure your nipple lengthwise or from top to bottom, it typically doesn't matter. The important part is to ensure you're getting an accurate measurement in millimeters. Measuring in millimeters ensures you'll get the most accurate measurement as the size differences are quite small and exact.

If this sounds like an odd task that you don't want to undertake on your own, don't worry – many lactation consultants offer flange fitting services. Either way, determining the correct flange size is essential for providing optimal comfort and efficiency during the pumping process.

Does Your Flange Size Change?

As a new mother, you may be surprised to learn that your flange size can vary as you embark on your breast-pumping journey. Whether you're an experienced mama or a newbie, flange size isn't something that tends to stay the same throughout the process. Just as your nipples changed throughout your pregnancy, they'll likely change as you breastfeed, too.

While this may seem intimidating at first, it simply means that you have to reassess your flange size periodically and make sure it's still working for you and your needs. If you're a new mama, use this quick sizing guide to help you understand when you should take time to remeasure for a potential new fit.

After 4-6 Weeks

When your breast pumping kit first arrives you'll want to measure to ensure you have the right flange size. Or, if you purchased a kit with varying flange sizes, you'll be measuring to ensure that you're using the correct size. Either way, after about four to six weeks of pumping, it makes sense to go back and remeasure your breasts.

This is because most women experience swelling post-partum that can affect the initial sizing of their breast-pumping accessories. After about four to six weeks, this swelling should have gone down and your sizing might have changed.

Likewise, during this time, you might notice more discomfort as your breasts are swollen and sensitive. If you believe you have the right flange size but are experiencing friction, you can try using nipple balm to help soothe your nipples as you shift in between sizes.

After 4-6 Months

After about four, five, or six months it's likely time to replace the valves, membranes, and diaphragms on your breast pump. This makes this checkpoint on your breastfeeding journey the perfect time to remeasure your nipples for correct sizing as well.

Look for any discomfort or reduced milk flow. If you're pumping less than 4 ounces per session then you might have the wrong size. Likewise, if you notice pinching or discoloration at this stage, it could be a sign that you're using the wrong size. Or, it could simply mean that it's time to replace your flanges.

You'll want to replace flanges and the other accessories mentioned above every three months if you're pumping full-time.

Get the BabyBuddha Complete Kit 

Looking to make breast pumping a more pleasant and comfortable experience? Look no further, the BabyBuddha Complete Kit has got you covered. It boasts 14 different pumping modules and two flanges along with all of the accessories required for a smooth pumping experience.
While our standard kit comes with a 24mm flange size, you can purchase other flange kits to ensure you have the correct breast pump flange size for whatever your needs. Click here to check out the complete kit or feel free to get in touch with questions regarding sizing!

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