Breast Pump Flanges: Choosing the Right Size and Type

Learn how to choose the right breast pump flange size and type for comfort and efficiency, with practical decision rules and product guidance.

Publishing teamXI LANGS Editorial

PublishedOct 20, 2026

Page updatedOct 20, 2026

Reading time4 minutes

Breast Pump Flanges: Choosing the Right Size and Type

Quick answer

For the most comfortable and efficient pumping, choose a flange that matches your nipple diameter and fits your pump model. Start with a standard size, then adjust based on fit and comfort—using inserts or different flange types as needed.

Why flange size and type matter

The right flange size is key to comfortable, efficient pumping. If the flange is too small, your nipple may rub against the tunnel, causing pain. If it's too large, areola tissue can be pulled in, reducing milk output. Using the correct size helps maintain a good seal and comfort.

Flange type also matters. Some flanges have soft, flexible edges that can feel more comfortable, while others are designed for wearable pumps with a different fit. Consider your pump model and how you plan to use it when choosing.

Trade-offs: soft edges vs. rigid flanges

Soft, flexible flanges can be more comfortable, especially for sensitive nipples, but they may not provide the same rigid support as harder plastic flanges. Rigid flanges can hold their shape better, which some moms prefer. There is no universal 'best'—it depends on your comfort and how your body responds.

If you're unsure, try a standard flange first and see how it feels. If you experience discomfort, consider a flange with soft edges or an insert that adjusts the fit.

Decision rules for choosing your flange

Measure your nipple size: Use a ruler or a sizing card to measure the diameter of your nipple (not the areola) after a few minutes of pumping or when it's stimulated. Choose a flange that is 1-2 mm larger than your nipple diameter.
Check your pump model compatibility: Ensure the flange you choose is compatible with your pump. ComfortFit flanges work with all Lansinoh pumps, while DiscreetDuo flanges are specifically for the DiscreetDuo wearable pump. Thrive inserts fit PowerPump and wearable cup flanges.
Consider your comfort needs: If you have sensitive nipples or experience discomfort with standard flanges, try a flange with soft, flexible edges like the ComfortFit. If you need a more precise fit, consider using inserts that adjust the size without buying a whole new flange. If you're between sizes, go with the larger flange and use an insert to fine-tune the fit.
Replace worn parts promptly: Inspect flanges before each use and replace any that show signs of wear or damage. Worn flanges can reduce suction and efficiency. Keep a spare set on hand for when you're away from home. Order a spare set when you buy your pump so you're never caught without a clean part.

Flange options to consider

ComfortFit® Breast Pump Flanges for Signature Pro and Smartpump: Lansinoh® Breast Pump Flanges ensure an ideal fit to maximize pumping efficiency. Compatible with all Lansinoh® pumps, ComfortFit® Flanges have soft, flexible edges for comfortable pumping and a secure seal. BPA and BPS Free. These flanges offer a soft, flexible edge that can improve comfort and seal, making them a good choice if you have sensitive nipples or want a secure fit with any Lansinoh pump.

ComfortFit® Breast Pump Flanges for Signature Pro and Smartpump
DiscreetDuo Wearable Pump – Flanges (1 count only): DiscreetDuo Wearable Pump – Flanges (1 count only). Replace pump parts regularly to ensure the best functionality throughout your pump’s life. Inspect breast pump parts before each use and replace any noticeably worn or damaged parts. Please order 2 of these for both pumps. If you use the DiscreetDuo wearable pump, this flange is the exact replacement part you need, and you'll want to order two so you have a spare for each side.

DiscreetDuo Wearable Pump – Flanges (1 count only)
Thrive Flange Inserts for PowerPump Set & Wearable Cup Flanges: Thrive Flange Inserts for PowerPump Set & Wearable Cup Flanges. A spare set of parts when you need them! Great to have on hand when you’re pumping away from home and need an extra set of clean parts. Or keep it on hand to replace parts that wear over time. These inserts are useful for adjusting the flange fit on PowerPump and wearable cup flanges, and having a spare set ensures you're never without a clean part when you're away from home.