Choosing your Pump Size: 3 Easy Steps to the Getting Your Right Fit

Woman with breast pump that fits properly

If pumping is part of your new parent experience, then having a well-fit pump is an important part of your journey, but it can also be confusing to try to figure out how to get your Goldilocks fit, where your pump fits you just right.

In this blog post, I want to help you understand how to use a nipple sizing ruler to make sure your pump flange is the exact right fit for your body so you can get the most amount of milk without hurting yourself in the process, in 3 easy steps.

STEP 1: Get a Ruler

To get the custom fit pump for anything for your body, you have to measure it first, and that means getting the right tool for the job. Luckily, there are several ways to measure your nipples, and they all work.

The fastest way to get a sizing ruler for your nipples is to just print one off at home. If you don’t have one, you can click right here for my flange sizing chart. If you are using a printable sizing chart, the most important thing you need to do is make sure the scale is correct when you are printing it.

Even if it’s off by 1-2 mm, that’s going to make a difference in your measurement. Here is a video about how to print my ruler, and make sure you measure you measure the 1x1 inch box with a ruler to make sure your printing is accurate.

If you don’t have a printer you can also just purchase a metric circle ruler from Amazon for under 10$. If you happen to be an electrical engineer and have digital calipers at home that measure in metric, you can use those too. You can also just use a straight metric ruler, but these are the least accurate way to get your starting number because it’s hard to see.

Once you have your ruler, you’re ready to move to step 2

Expert Tip:

Your goal here is to find out what the actual diameter or the width of the widest part of your nipples is, in metric, because that's how the pump flanges are measured.

STEP 2: Measure Your Body

Now that you have a way to measure your body, it’s time to understand the size of your nipples.

If you have printed off my guide (again here is the link if you haven’t…go do that step first), you just need to cut out the holes that most closely match your nipples and then slide the ruler over your nipple to see which one is the closest fit.

It should be snug because you want the exact size of your nipple. If you are using calipers, you can do the same thing, but just make sure you don’t compress your nipples here. The size that you get in mm is the size of your nipples and the number you'll use to start experimenting with to figure out your perfect fit. 

Your nipple is designed to stretch and your areola is not, and when it stretches over and over again, that can cause it to become inflamed and painful, so you want to get the measurement for your nipples ONLY. 

Expert Tip:

Eyeballs can not accurately measure in millimeters. So if someone has measured you just by looking at your body, without actually measuring it, they did NOT measure you. They guessed. They could be right, but most likely, they are very off.


STEP 3: Find Your Custom Fit

Now that you have your nipple size, you have your starting point for experimenting for your body.  Everybody’s BODY responds differently to pumping, and that means that no one magic measurement number works across the spectrum.

Some people’s nipples get larger. Some stretch when pumping, making them smaller, and others stay the same size, and you don’t know which body you have until you experiment with pumping.

Here’s a chart with a general sizing guideline for depending on which body type you have, but this is just a starting point for you to experiment with. Which size works for you will likely fall within one of the three sizes I’ve listed below, and you won’t know until you test it.

Think of it like your own personal 7th-grade science experiment that is much more useful than seeing how fast breast molds. You simply use each different size at different times over a few days and see which one works best for you, and gives you the most amount of milk for the least amount of work without causing pain and damage.

Expert Tip:

When you are in the learning process of experimenting to find the right size for your body, just really you can catch signs of damage early before they snowball into something bigger. I’ve seen some significant nipple trauma in my clinical practice, and trust me, you do not want to go there.

Now that you understand how to measure and get your right fit, here are a couple of important things you need to know about pump fitting.

Your body isn’t symmetric.  
And that means your nipples might be different sizes, so you need to get the right fit for each nipple. When you are comparing output, make sure you are comparing that side to itself…the understudy may never make as much as the star performer, but you want to make sure you help it do its best.

Wait to get your perfect fit until all the fluid from labor is gone. 
Your breasts and nipples change during pregnancy and if you get fluid during labor it can change both the shape and the elasticity of your breast/chest tissue, so using the 24 that came with your pump (if you need to pump at all) is a good starting point. Wait to measure for your ideal fit until all that fluid you got during labor is gone from your body. You’ll know because you can find your ankles again.

Enlist a professional if you need it.  
It can be hard to measure your nipples yourself, especially if it’s hard to see your nipples, and this is where a good professional can help, especially if you are already working with a lactation consultant. They can double-check your size and help you visually inspect your flanges to see how they look in terms of fit, but how it feels and how much you produce trumps what it looks like, all day long.

Getting the right fit for your pump is more art than science, but it’s the science of measuring helps you get in the right ballpark of your right size. Once you measure your nipples and know your size, then it’s time to experiment to figure out what works best for you. Now it’s your turn to go experiment!

Let me know how it goes, and if you still need that ruler to get started, you can download it right here.


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