Flange Sizing Calculator & Measurement Guide
Pumping breast milk should never be painful. If you are experiencing pinched nipples, lingering pain, low milk output, or dreaded clogged ducts, there is a very high probability that you are using the wrong size breast pump flange.
The standard 24mm or 28mm flanges that come inside the box with most breast pumps are actually too large for the vast majority of women. Finding your true flange size is the most important step in protecting your milk supply and making your time on the pump comfortable.
Interactive Flange Sizing Calculator
Enter your nipple base measurement (in millimeters) before pumping to find your ideal flange size.
Your Recommended Flange Size:
How to Measure Your Nipples Correctly
To get an accurate result for the calculator above, you must measure the base of your nipple correctly. Do not include your areola in the measurement.
- Stimulate your nipple: Make sure your nipple is erect before measuring. Do this before a pumping session, as pumping temporarily swells the tissue.
- Use a measuring tool: Use a printable nipple ruler, a digital caliper, or a standard ruler with millimeter (mm) markings.
- Measure across the base: Measure straight across the base of the nipple (the horizontal diameter). Again, do not measure the darker skin around it (the areola).
- Measure both sides: It is incredibly common for women to have two different sized nipples! You may need a 19mm flange on the left and a 17mm flange on the right.
The “Coin Hack” for Quick Measurement
Don’t have a ruler with millimeter markings? You can use standard US coins to estimate your nipple base size. Hold the coin over your nipple. Your nipple should fit entirely inside the inner flat circle of the coin.
| Coin Size | Measurement in mm | Try This Flange Size |
|---|---|---|
| Dime | 17.9 mm | 19 mm to 21 mm |
| Penny | 19.0 mm | 21 mm to 22 mm |
| Nickel | 21.2 mm | 24 mm |
| Quarter | 24.2 mm | 27 mm to 28 mm |
If you have the correct flange size but your nipple still stretches extremely far down the tunnel during pumping, you may have “elastic nipples.” This can cause low milk output because the tissue stretches and blocks the milk ducts. Consider looking into silicone inserts or specialized flanges (like Pumpin’ Pals or Lacteck) which are designed to hold elastic tissue in place.
Signs Your Flange is the Wrong Size
Even if you measured perfectly, your body will ultimately tell you if the fit is right. Keep an eye out for these red flags while logging your sessions in your Pumping Tracker:
Signs your flange is TOO BIG:
- A large portion of your areola is being pulled into the tunnel of the flange.
- The flange constantly shifts or loses suction while pumping.
- You have a thick, white, or red ring around the base of your areola after pumping.
Signs your flange is TOO SMALL:
- Your nipple rubs against the sides of the tunnel as the pump pulls.
- Your nipple turns white (blanching) or purple during or after pumping.
- You feel stinging or pinching, and milk output is lower than normal.
Remember, your nipple size can change throughout your postpartum journey. If pumping suddenly becomes uncomfortable after months of success, remeasure yourself! A simple flange size adjustment can drastically increase your milk supply and save your pumping journey.