How to Measure Your Breast Pump Flange Size

Finding the Right Flange Size for Comfortable & Effective Pumping

One of the most common reasons pumping feels uncomfortable or doesn’t fully empty the breast is using the wrong flange size. Whether you’re using an Ardo breast pump or another brand, choosing the correct flange or insert size can improve comfort, help maximize milk removal, and make your pumping experience more effective.

This guide explains how to measure your nipple correctly, how to choose the right flange or insert size, and how the Ardo Melia makes sizing even easier. For additional breastfeeding and pumping tips, visit our Helpful Resources page.

The flange is the funnel-shaped part of the breast pump that fits over your nipple. During pumping, your nipple should move freely inside the tunnel without excessive rubbing or pulling in too much surrounding areola.

A flange that is too small may:

• Cause pain or pinching
• Restrict milk flow
• Reduce milk output
• Cause nipple rubbing

A flange that is too large may:

• Pull excessive areola into the tunnel
• Cause discomfort
• Reduce pumping efficiency
• Make it more difficult to fully empty the breast

Finding the correct size can make pumping more comfortable while helping maintain your milk supply.

Learn more about choosing the right breast pump in our Breast Pump Comparison Guide.

For most breast pumps, measuring your nipple is simple.

Step 1

Measure your nipple after pumping or after using a warm compress, when it is fully extended.

Step 2

Measure only the diameter of the nipple at its base.

Do not include the areola.

Step 3

Measure both nipples individually.

Many parents have nipples that are slightly different sizes, so you may need a different flange or insert on each side.

Once you’ve measured your nipple diameter, select the flange or insert size recommended by your breast pump manufacturer.

A properly fitted flange allows your nipple to move comfortably within the tunnel while minimizing excess areola being pulled into the pump.

If you’re unsure which size to choose, consult your breast pump manufacturer or an International Board Certified Lactation Consultant (IBCLC).

One of the unique features of the Ardo Melia Wearable Breast Pump is that a convenient flange sizing ruler is built right into the product box.

Using the Melia sizing guide is easy:

1. Cut along the indicated line on the box to remove the sizing guide.
2. Place the guide over your nipple.
3. Measure the width of the base of your nipple only—do not include the areola.
4. Measure both nipples, as they may be different sizes.

The Melia includes a 24 mm breast shield and a 19 mm silicone insert, with additional silicone inserts available separately to help you achieve a more personalized fit.

Ardo Melia Silicone Inserts to find the size that’s right for you.

You may need a different flange or insert size if you experience:

• Pain during pumping
• Nipple rubbing against the tunnel
• Excessive areola pulled into the flange
• Reduced milk output
• Incomplete breast emptying
• Redness or swelling after pumping

If pumping continues to be uncomfortable, consider speaking with an IBCLC or healthcare provider for personalized guidance.

You can also browse our Helpful Resources for product videos, manuals, and additional pumping support.

Looking for more breastfeeding and pumping guidance? Explore these helpful resources:

• Breast Pump Comparison Guide – Learn the differences between wearable, electric, and hospital-grade breast pumps.
• Helpful Resources – Access product manuals, videos, FAQs, and troubleshooting guides.
• Insurance Eligibility – Find out how to order an Ardo breast pump through insurance.
• Melia Wearable Breast Pump – Learn more about the Ardo Melia and available accessories.

Choosing the correct flange size is just one part of a successful pumping journey. Explore our additional breastfeeding and pumping resources, product guides, and instructional videos to help you get the most from your Ardo breast pump.