A breast pump is only as effective as its fit. The flange, the cone-shaped piece that sits against your breast, needs to match your nipple diameter closely for the pump to create proper suction, extract milk efficiently, and avoid causing pain. Most pumps ship with a standard 24mm or 28mm flange. If your nipple is smaller than that standard size, the stock flange creates a loose seal, allows too much areola into the tunnel, and reduces both comfort and output. Flange inserts solve this problem without requiring you to buy a completely new flange set. BabyBuddha offers inserts in 17mm, 19mm, and 21mm sizes designed for use with BabyBuddha Express Cups Plus, along with a complete range of EasyFit Flanges for moms who need a different base size entirely.
Summary: Flange Inserts
Flange inserts are silicone rings that sit inside your existing flange tunnel, reducing its diameter to match your nipple size. They improve suction efficiency, increase comfort, and can boost milk output for moms whose stock flanges are too large. Most pumps ship with 24mm flanges, but many women measure smaller. Inserts cost $10 to $25 and are a more affordable first step than buying a complete new flange set. The right insert size is your nipple diameter plus 1 to 2mm of clearance, and your size may change during your pumping journey, so re-measuring periodically is important.
Key Points
- What they are: Silicone rings or sleeves that reduce your flange tunnel diameter by fitting inside the existing flange.
- Why they matter: A flange that is too large reduces suction efficiency, causes areola swelling, and can decrease milk output.
- Common sizes: Inserts typically come in 17mm, 19mm, and 21mm, designed to pair with standard 24mm or 28mm flanges.
- How to size: Measure your nipple diameter at the base and add 1 to 2mm. That is your target tunnel size.
- Cost: $10 to $25 per set, significantly cheaper than buying a complete new flange kit.
- Asymmetry is normal: Many moms need a different insert size for each side. This is common and expected.
- Size changes over time: Nipple size fluctuates with engorgement, supply regulation, and the natural course of breastfeeding. Re-measure if comfort or output changes.
- Pain is not normal: If pumping hurts, check your flange fit before adjusting suction. Inserts are often the fix.
Find Your Fit
The right flange size makes a bigger difference than the pump itself. Browse BabyBuddha flange inserts and sizing options to find the size that fits your body.
What Flange Inserts Are and How They Work
Flange inserts are silicone rings or cushioned sleeves that sit inside the tunnel of your breast pump flange. They reduce the internal diameter of the tunnel to match your nipple size more closely, creating a snugger fit that directs suction more effectively. Inserts are sold in specific millimeter sizes, typically 17mm, 19mm, and 21mm, and pair with the standard 24mm or 28mm flange that most pumps ship with. According to Cleveland Clinic's flange sizing guidance, finding the right flange size is one of the most important steps for comfortable and effective pumping.
Inserts are not a separate flange. They modify the flange you already have. This makes them significantly cheaper than buying multiple flange sizes and allows you to fine-tune your fit without replacing your entire setup. BabyBuddha inserts are designed for use with the BabyBuddha Express Cups Plus and come in 17mm, 19mm, and 21mm sizes, covering the range where most moms who need a smaller fit will land.
Why Flange Fit Matters More Than Most Moms Realize
Signs Your Flange Is Too Large
When your flange tunnel is too wide for your nipple, too much areola gets pulled in during each pump cycle. This causes swelling, friction, and redness around the nipple and areola. You may notice your nipple moving side to side in the tunnel rather than staying centered, white spots or creasing on the nipple after pumping, or pumping sessions that take longer than expected because suction is not being directed efficiently. Output can drop or plateau even with a consistent pumping schedule because the pump is losing suction around the excess space.
Signs Your Flange Is Too Small
A flange that is too tight compresses the nipple against the tunnel walls. This causes pain, restricted milk flow, and potential nipple damage. You may see the nipple appearing pinched, compressed, or blanched, meaning white, during or after pumping. Clogged ducts can develop because milk cannot flow freely past the compression point. If pumping causes consistent pain that does not improve after the first minute of your session, a too-small flange is one of the most likely culprits.
How the Right Fit Improves Output
A properly fitted flange centers the nipple in the tunnel with about 1 to 2mm of space on each side. This allows the nipple to move gently with each pump cycle, stimulating a natural letdown response and enabling efficient milk removal. A 2025 pilot study published in the Journal of Human Lactation found that using a flange sizing tool to identify smaller-fit sizes improved comfort and output compared to the standard 24mm flange. Many moms who think they have low supply actually have a fit problem. Correcting the flange size is the first troubleshooting step lactation consultants recommend before changing pump settings or adding supplements.
Not Sure If Your Flange Fits?
A quick measurement can tell you whether inserts will improve your pumping experience. Use BabyBuddha's flange sizing guide to measure and find your ideal tunnel diameter.
How to Measure for the Right Flange Insert Size
Accurate measurement is the foundation of a good fit. Aeroflow's flange size chart provides a visual reference for nipple measurement, and the process is straightforward.
Step 1: Stimulate your nipple before measuring, because your nipple will be in a similar state during pumping. Use a warm compress or gentle hand expression to bring the nipple to its pumping diameter.
Step 2: Measure your nipple diameter at the base, the widest point where the nipple meets the areola, using a ruler marked in millimeters or a flange sizing tool. Measure in millimeters for precision.
Step 3: Measure both sides. Nipples are often slightly different sizes, and many moms need a different insert for each breast. This is completely normal and more common than you might expect.
Step 4: Add 1 to 2mm to your measurement. This is your target flange tunnel diameter. Most moms find the best combination of comfort and suction efficiency with 1 to 2mm of clearance around the nipple.
Step 5: Choose the insert size that brings your existing flange tunnel down to that target diameter. If your flange is 24mm and your target tunnel size is 19mm, use a 19mm insert.
Important: Nipple size can change during your pumping journey, especially in the first 8 weeks postpartum as supply regulates and engorgement patterns shift. Re-measure if you notice changes in comfort or output. BabyBuddha's flange sizing guide walks through the measuring process with visuals and size recommendations specific to BabyBuddha products.
BabyBuddha Flange Inserts and Sizing Options
BabyBuddha offers a complete range of flange sizes and inserts to accommodate the majority of pumping parents. BabyBuddha inserts come in 17mm, 19mm, and 21mm sizes, designed for use with the BabyBuddha Express Cups Plus. They are made from soft, medical-grade silicone and snap securely into the flange tunnel.
For moms who need a different base flange size rather than an insert, the BabyBuddha EasyFit Flange Kit includes 4 sizes for the BabyBuddha 2.0 and other pump models. The Original Flange Kit offers 3 sizes. Individual flanges are also available in 24mm, 28mm, and 32mm for moms who need larger sizes.
All BabyBuddha flanges and inserts use the same connection system, so they are interchangeable across BabyBuddha pump models. If you start with the BabyBuddha 2.0 and later add a wearable, your flange sizing carries over. The full sizing range from inserts through flanges covers 17mm to 32mm, accommodating the vast majority of nursing parents.
Common Flange Insert Mistakes and How to Avoid Them
Even with the right insert, a few common errors can undermine your fit.
- Using an insert that is too tight: If the insert compresses or pinches your nipple during pumping, go up one size. A snug fit does not mean a tight fit. You should see your nipple moving freely within the tunnel.
- Not re-measuring over time: Nipple size changes with engorgement, supply regulation, and the natural progression of breastfeeding. What fits perfectly at 2 weeks postpartum may not fit at 8 weeks. Re-measure whenever comfort or output shifts.
- Using inserts from a different brand: Inserts designed for one pump brand may not seal properly inside another brand's flanges. A poor seal between the insert and the flange reduces suction efficiency. Use inserts designed for your specific pump.
- Ignoring asymmetry: Many moms need a different size insert for each breast. Using the same size on both sides when your nipples are different diameters means at least one side has a suboptimal fit.
- Assuming pain is normal: Pain during pumping almost always indicates a fit problem. Inserts or a different flange size should be the first fix, not higher suction. Increasing suction on a poorly fitted flange makes the problem worse.
When to Use Inserts vs Buying New Flanges
Inserts and new flanges solve the same problem from different angles, and knowing which you need saves money and time.
Use inserts if your current flange is close to the right size but slightly too large, and you want an affordable fix without replacing the entire setup. Inserts cost $10 to $25 per set, compared to $20 to $40 for a new flange kit. They are the most economical first step for moms whose stock flange is 24mm or 28mm but whose nipple measures 17mm to 21mm.
Buy new flanges if you need a size significantly different from your current flange, or if your pump requires a specific flange type that inserts cannot modify. Some moms find that their nipple diameter falls outside the insert range entirely, or that the base flange shape of their pump does not accommodate aftermarket inserts well.
Some moms use both approaches: start with a flange kit for the best base size, then add an insert if their nipple size changes postpartum. This layered approach gives you maximum flexibility as your body adjusts during the first months of pumping.
Inserts, Flanges, or Both?
BabyBuddha offers inserts from 17mm and flanges up to 32mm, all interchangeable across BabyBuddha pumps. Browse the full flange and insert collection and find your size.
