Pumping should never hurt

Pumping should never be painful. If you are experiencing discomfort, rubbing, or noticing that your milk supply isn’t what it should be, the culprit might be your flange size. Much like finding the right shoe size, using the correct breast pump flange—the funnel-shaped part that touches your breast—is essential for both comfort and efficiency.

Whether you are using a versatile pump like the Ameda Glo or another model, here is everything you need to know about measuring yourself for the perfect fit.

Why Does Flange Size Matter?

Using the wrong size isn’t just uncomfortable; it can impact your breastfeeding journey:

• Too Small: A tight flange causes painful friction and can pinch your milk ducts. This prevents the breast from emptying properly, which may eventually lower your milk supply.
• Too Large: A flange that is too big pulls too much of the areola (the dark circle around the nipple) into the tunnel, leading to swelling, bruising, and discomfort.

When the fit is just right:

• Your nipple moves freely in the tunnel.
• Little to no areola is pulled into the tunnel.
• The breast feels soft and empty after pumping.
• You feel no pain—only a “tugging” sensation.

How to Measure for the Right Flange Size

Step 1: When to Measure

The best time to measure is before you begin pumping. Your nipples can temporarily expand during a pumping session, so measuring beforehand gives you the most accurate baseline.

Step 2: Measure the Nipple Diameter

To find your size, measure the diameter of the base of the nipple (the part that sticks out). Do not include the areola in your measurement.

• Using a Ruler: Use a ruler with millimeter (mm) markings. Measure across the very base of your nipple.
• The South African “Coin Hack”: If you don’t have a ruler handy, you can use common South African coins as a quick reference:
  • 10c coin: 16.00 mm
  • 50c coin: 19.00 mm
  • R1 coin: 20.00 mm
  • R5 coin: 26.00 mm

Step 3: Download Our Sizing Tool

For the most accurate results, we recommend using a dedicated tool.

Print this guide at 100% scale for accuracy. Cut along the dotted lines to measure your nipple diameter easily at home.

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Step 4: Choose Your Flange Size

Once you have your nipple measurement in millimeters, you need to add a little bit of “room to move.”

The Golden Rule: Choose a flange size that is 2mm to 3mm larger than your nipple measurement.

• Example: If your nipple measures 19mm, a 21mm or 22.5mm flange will likely be your best fit.
• Example: If your nipple measures 22mm, you should look for a 24mm or 25mm flange.

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Signs of a Good Fit vs. a Poor Fit

Observe how your body responds during a pumping session:

The Perfect Fit	Too Small	Too Large
Nipple is centered and moves freely.	Nipple rubs against the sides of the tunnel.	A large portion of the areola is sucked into the tunnel.
A small gap exists between the nipple and the walls.	Feels like “sandpaper”; leads to redness or cracked skin.	Can lead to “doughnut-shaped” swelling around the nipple.

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A Note on the Ameda Glo

One of the reasons many mothers prefer the Ameda Glo is its compatibility with a wide range of flange sizes and inserts. To ensure that most mothers can find their perfect fit right away, the Ameda Glo conveniently comes with four different flange sizes included in the box. Because every mother is unique—and because your size can actually change throughout your journey—it is incredibly helpful to have a pump system that offers these various options to adapt to your needs from day one.

Final Expert Tips

1. Check Both Sides: It is very common for your left and right nipples to be different sizes. Always measure both!
2. Re-measure if Pain Starts: Your body changes as your milk supply stabilizes. If pumping becomes uncomfortable after a few months, take a moment to measure again.
3. Consult a Professional: If you are struggling to find a comfortable fit or are worried about your supply, a certified lactation consultant can provide a personalized fitting and support.

By taking five minutes to measure correctly, you ensure that your pumping journey is as productive and comfortable as possible. Happy pumping!