How to Choose the Breastshield Size That’s Right For You

How to Choose the Breastshield Size That’s Right For You

Whether you’re an exclusively expressing mom, or just want to pump now and then to have extra milk available, pumping should be as painless and efficient as possible. A great pump goes a long way, but even if you have the best breast pump in the world, expressing will still be really difficult if you aren’t using the right breastshield size.

Unfortunately, determining the right size breastshield for you can be a bit of trial and error. Many first time mums don’t even realise that breastshields come in different sizes. They struggle with enduring pain while pumping. If you know a mum like this, share this post with her!

Here are the top factors to consider when working out your breastshield size. Remember, you may need to try a few sizes to get the final fit (which may change over the course of your time breastfeeding!) but this should get you off to a good start.


The Basics of Breastshield Size

Let’s start off with some basic definitions and breast pump parts.

The difference between a flange and a breastshield

When you’re trying to figure out sizing you may notice that people seem to use the terms ‘flange’ and ‘breastshield’ at different times. Very often, these terms will be used interchangeably. But for reference purposes, the flange is the little ‘tunnel’ part of a breastshield that the nipple is drawn into, whereas the breastshield refers to the entire ‘funnel’ plus the bits that the bottle, tubing etc will connect to.

There are two types of breastshields

There are two types of breastshields that are very common – one-piece breastshields (like the Pumpables Original All-In-One Breastshield) and two-piece shields. In a one-piece, the flange is connected. In a two-piece shield, the flange is separate and plugs into another connecter piece.

Breastshield size refers to your nipple size (not your cup size)

When we’re talking about using a different breastshield size,  it’s actually the flange part of the breastshield that is changing! And the size relates to your nipple, not your cup size. It’s very common for mums (and dads) who are new to pumping to think that the breastshield size is determined by your cup size. No! It’s all about your nipple size – diameter of the nipple, specifically – though nipple elasticity (or how stretchy your nipple is) also comes into play.


How to work out our your best breastshield size

Start by measuring your nipple diameter

To get a starting point on your breastshield size, select a flange that leaves plenty of room around your nipple and begin pumping. Pump for 5 minutes. When you pump, your nipple will swell, so it’s important to take the measurements after you pump. Then, you can use the nipple ruler to see which hole is the most snug fit around your nipple.  Make sure it is not so roomy that excess areola is being drawn in. If possible, do this over a few pumping sessions so you can make sure your measurement is consistent.

If this is your first time pumping, you should use this nipple diameter measurement to pick your breastshield size, giving you a great starting point.

Tip: don’t assume that the size that came with your breast pump is right for you.


Once you’re pumping, reassess

Once you’ve started pumping, you’re going to have a lot more information to go on to make your size choice. Unfortunately, this is kinda like buying shoes. You can measure your feet and do the best job you can, but until you’re wearing those shoes on a dance floor, up a mountain or wherever you plan to wear them, you won’t really know if they fit right until you’re in the middle of the activity. It’s a pain because it does mean additional costs if you end up having to buy another size, but if you are pumping regularly we really recommend trying different sizes to make sure you get the best fit.


Is pumping causing pain?

Even if you measured your nipple diameter and feel you picked the right flange size, if you’re in pain once you start pumping you should assume that something isn’t right – most likely the shield fit. Some new moms experience nipple pain while their nipples get used to breastfeeding and expressing, and lightly lubricating the inside of your flange with some coconut or olive oil may help. If you’re still feeling pain, try another breastshield size.


Your suction preference when pumping

When you pump, you will set the vacuum level (suction strength) on your pump to the highest level you can without feeling any discomfort. When you start to feel discomfort as you increase the vacuum level is very individual and some women can tolerate a higher suction strength than others. If you are someone who uses a higher suction strength when pumping, then your nipple size and length is likely to increase more when you pump, and this will affect the breastshield size that is right for you.


Nipple elasticity

Elasticity, or how stretchy your nipples are, is another factor. Some women’s nipples stretch out further down the flange than others. If your nipple hits the end of the flange when you pump, it can be a sign that the flange size is too big. Swapping to a smaller size (so that less nipple can enter into the flange) may fix the problem. However, if your nipple just has a tendency to stretch, choosing a two-piece breastshield can help. These shields tend to have a longer flange, giving your nipple more room to stretch out.


Milk output

You’ve measured your nipple, chosen a breastshield size and you’re pumping without any pain–yet the milk output isn’t great. Check your positioning or try another size. Using the wrong shield size can impede milk flow by causing milk ducts to either be blocked or not stimulated. Trial and error!


You may need more than one breastshield size

And for the final, confusing factor, be aware that you may need different shield sizes over the course of your pumping journey! You may find that each breast has a different nipple size, you may find that your nipple size changes over the day, and you may also find that the best shield size for you goes up or down as time goes on.



Having the right size flange is great, but if it's not positioned correctly it could still be causing issues.  Make sure that the nipple is centered and as far down the tunnel as possible, and that the plastic funnel is flush to the skin all the way round with no gaps or air bubbles. Once the shield is correctly positioned, switch the pump on and a suction seal should form behind the nipple.


If the Flange Fits…

If your flange is just right and perfectly positioned, you should notice more comfortable feeding, and hopefully this will translate into more milk output and an overall better experience for you. It is so important that pumping is comfortable, and flange size is probably the number one contributing factor to comfort. Make sure you experiment and get this right!

This is why we have a selection of six sizes to choose when purchasing the Pumpables Genie Advanced or the Pumpables SuperGenie because we really want to make it easy for you to find the perfect fit. If you have any questions at all about this post, or are not sure you’re using the right flange size, then get in touch and we can give you some tips to help.

Happy pumping, mamas!

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Are you worried about shield fit? Download the Pumpables measuring tool to ensure you're using the right size