A Step-by-step Guide to Measure Your Breast Pump Flange Size

Knowing how to measure your nipples and find the right flange size is everything when it comes to comfortable pumping and optimal milk flow. Pumping should also never be painful. That’s why Medela offers various flange sizes.

Do breast pumps vary in sizes?

Breast pumps are designed to fit your breasts, and more specifically, your nipples, which can even vary from breast to breast. To make sure your breast pump does its job, make sure you learn about breast pump flange sizes, also known as breast shields. Flanges are designed to fit directly over your nipple. When you pump, your nipple ( make sure it is not your areola!) is gently pulled into the tunnel of the flange, just like the baby would pull on it during breastfeeding. Getting the flange size right is crucial for effective milk removal, and equally important, your comfort.

How do I measure my flange size so that my breast pump works?

To find your ideal flange size, start by measuring your nipple. Simply follow the instructions below.

1. To measure your nipple size, use a ruler or measuring tape to figure out the size of the diameter of your nipple at the base (across middle) in millimeters (mm). Remember to not include your areola.

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2. Based on your measurement, you can determine your Medela flange size by adding 4 mm.

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Example: If your nipple size measures 16 mm in diameter, the recommended Medela flange size is 21 mm.

3. Test your flange size.

Center the nipple and gently hold the flange against your breast.

If the nipple is centered and moves freely this is a correct fit.

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The flange size is too small if:

The nipple rubs along the side of the tunnel.
In this case, try a larger size.

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The flange size is too large if:

The nipple and excessive areola are pulled into the tunnel.
In this case, try a smaller size.

You can also download a PDF guide “Choosing your Medela breast shield size” or watch the animation below. Both contain additional information about flange sizes and reasons to try a new size.