The flange is the breast pump part that comes in contact with your body when placed onto the breast and nipple, forming a vacuum seal with the areola. It's shaped like a funnel. The flange draws your nipple into the tunnel of the pump where milk is extracted.
Flanges are typically made of plastic or silicone and come in various sizes to accommodate different nipple dimensions.
Some breast pumps come with multiple flange sizes or offer smaller inserts or cushions to customize the fit within the flange. This reduces the opening of the tunnel where the nipple enters and allows for a more comfortable and effective pumping experience.
The fit of your breast pump’s shield or flange has a big impact on both your comfort and milk output. A properly fitted flange helps you express more milk, prevents nipple pain or damage, and makes the whole pumping experience more effective and comfortable. That’s why it’s so important to measure your nipple size accurately.
Flange sizes typically range from 13mm to 36mm, depending on the brand. This measurement refers to the start of the flange tunnel—not the opening itself. Modavista breast pumps come with a standard 24mm flange, along with a 27mm option for mums with larger nipples. We also offer inserts from 15mm to 21mm to suit a variety of nipple sizes.
Your nipple should comfortably fit within the flange tunnel without rubbing or pinching. It should snug nicely inside the tunnel of flange. The areola should not be sucked into the tunnel.
If the flange is too small, your nipple might rub against the sides of the flange causing discomfort. If the flange is too large, the areola may be sucked in, which can reduce milk output and cause pain.
Nipple rubbing against the flange
Nipple snug nicelu inside the tunnel of flange
Nipple rubbing along aerola is being sucked into the flange
To determine the best flange size for you, you’ll need to measure your nipple first.
Step 1: Stimulate your nipple to make it perk up.
Step 2: Hold the ruler at a perpendicular angle and line the 0 scale with your nipple base at the same horizontal line, also with the ruler edge meet your areola.
Step 3: Get the millimeters number between the nipple base and the nipple top, and the size measuring is done.
Step 1: Stimulate your nipple to make it perk up.
Step 2: Place your nipple into the holes one by one to find out which one you can comfortably fit your nipples into, in a way that your nipple can be out through the hole totally, also the ruler can touch the areola at the same time.
Step 3: Get the size of the holes, then the size measuring is done.
Modavista includes a handy nipple ruler with holes in the breast pump set to make measuring a breeze. Please note that your left and right nipples may have different sizes, so please measure them both to get the exact size of them.
We recommend adding 1-3mm to your nipple measurement to determine your ideal flange size.
Because nipple size can fluctuate when pumping, choosing a flange 1-3mm larger often provides a more comfortable fit. For personalized guidance, refer to our flange size chart below.
| Nipple Measurement | Recommended Size | What I Should Purchase |
|---|---|---|
| 11-13mm | 15mm | 15mm Insert |
| 13-15mm | 17mm | 17mm Insert |
| 15-17mm | 19mm | 19mm Insert |
| 17-20mm | 21mm | 21mm Insert |
| 21-23mm | 24mm | Included |
| 24-26mm | 27mm | 27mm Insert |
| 27-29mm | 30mm | Not included |
*Please stimulate your nipple to make it perk up before measuring the size
Remember, every mum is different. While a 1–3mm fit works well for many, it’s important to listen to your body during pumping. It’s normal for your nipple to lightly touch the sides of the flange tunnel, but if you feel any rubbing, discomfort or pain, that’s a sign the fit may not be quite right. Don’t hesitate to try a different size—finding the perfect fit can make all the difference.
Nipple movement: Your nipple should move smoothly in and out of the flange tunnel without causing pain or leaving air gaps.
Areola involvement: Only a small part of your areola should be drawn into the tunnel while pumping.
Comfort: Pumping should feel comfortable — there should be no pain or discomfort at any stage.
Nipple condition: After pumping, your nipples should look healthy, with no signs of redness, blistering, or cracking.
Yes, it’s possible! Your breasts and nipples can change throughout your breastfeeding and pumping journey—especially between the third trimester, after birth, and as you continue to pump. That’s why it’s a good idea to regularly check your flange size to ensure the best fit and comfort.
If you're measuring before baby arrives or before you begin pumping, we recommend adding 1–3mm to your nipple measurement to allow for swelling that often occurs during pumping. A proper fit can make a big difference in both comfort and milk output.
Still unsure? Feel free to email us—we’re always happy to help!
Let’s get you back to your rhythm. We’ll size your flange in mm and ship a replacement if needed—so you can mother, uninterrupted.
The most commonly used flange size is 24mm. Many breast pump brands, including Modavista, offer a variety of sizes—such as 27mm flanges and inserts ranging from 15mm to 21mm—to suit different needs. It’s important to keep in mind that every woman is unique. Breast shapes and nipple sizes can vary greatly, so taking the time to measure your nipples ensures you’ll find a flange that fits comfortably and works effectively for you.
Yes, using the correct flange size can have a big impact on your milk supply. A well-fitted flange allows for more effective and comfortable pumping, which helps signal your body to continue producing milk efficiently.
Yes, you can. If too much of your areola is being pulled into the flange tunnel, it may mean the flange is too large. This can cause discomfort and may actually reduce how much milk you express. Ideally, only a small portion of the areola should enter the tunnel during pumping for the best comfort and milk flow.
If you’re between flange sizes, it’s a good idea to try using an insert first. Many brands, including Modavista, offer additional inserts to help you customise the fit. If you’re still unsure or between insert sizes, it’s generally recommended to go with the slightly larger option for better comfort and flow.
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