Breast Pump Flange Fit

Many breast pumps come with 24mm and 28mm flanges, but most breasts/nipples require sizes smaller than this. 

You may need a different size for each breast, and your flange size may change over time as your milk supply increases and then settles down. If you notice a change in comfort or output, consider re-measuring be sure you are still using the correct size. 

What Should Pumping Feel Like?

Pumping should feel like nothing or just a gentle tug—never pinching or pulling. If you're gritting your teeth or dreading your pump sessions, something needs to change.

For optimal stimulation, your nipple should gently touch the sides of the tunnel—this stimulates hormone receptors important for milk letdown and ongoing supply. Pumping isn’t just about “vacuuming out” milk; it’s about mimicking the body’s natural hormonal and mechanical feedback loops.

Flange insert kits often come with a measuring tool and multiple sizes that you can trial in your existing 24mm flanges to estimate the best fit. While inserts are often the only way to size wearable pumps, the hard plastic flange in your ideal size is likely to yield the best long-term results in both output and comfort.

Maymom is the recommended brand for hard plastic replacement flanges. So far, they are the only company to make different flange shapes, as well as a broad range of sizes. They sell a “Goldie Pack” (as in Goldilocks) on Amazon that includes 3 sizes, as well as single size pairs.