Flange Size Calculator
Helps you find out the correct flange size for your breasts depending on nipple size to ensure comfortable, pain and blockage-free pumping.
Refer to the text below the tool for more guidance on choosing the right breast pump flange size.
The average flange measures between 24 and 27 mm (0.95 – 1.06 in) but nipple size can vary significantly, sometimes even from one breast to another or at different times during the mother’s breastfeeding journey, hence the need to find out the correct flange size.
Using an incorrect flange may lead to discomfort and nipple damage, such as painful duct blockage, soreness or impact milk production. Typically, it is considered that the flange should be 3-4 mm larger than the nipple diameter.
The COMFY acronym may be used to check whether the correct flange size is used during breast pumping:
- Center Nipples Move Freely
- Only A Little Areola Tissues Should Be Pulled Into The Tunnel
- Motion Of Your Breast Is Gentle And Rhythmic
- Feels Comfortable Breast Pumping
- Yields Well-Drained Breasts
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Steps on how to print your input & results:
1. Fill in the calculator/tool with your values and/or your answer choices and press Calculate.
2. Then you can click on the Print button to open a PDF in a separate window with the inputs and results. You can further save the PDF or print it.
Please note that once you have closed the PDF you need to click on the Calculate button before you try opening it again, otherwise the input and/or results may not appear in the pdf.
Determining the Correct Flange Size
The breast pump flange, also known under the name of breast shield, is a funnel-shaped piece of plastic that is placed onto the nipple during pumping to create a vacuum seal and allow the facile drawing of milk from the breast.
The average flange measures between 24 and 27 mm (0.95 – 1.06 in) but nipple size can vary significantly, sometimes even from one breast to another or at different times during the mother’s breastfeeding journey, hence the need to find out the correct flange size.
Using an incorrect flange may lead to discomfort and nipple damage, such as painful duct blockage, soreness or impact milk production.
Typically, it is considered that the flange should be 3-4 mm larger than the nipple diameter. Please note the measurement focuses on the nipple diameter not the areola (the pigmented skin around the nipple). When placed on the nipple the flange tunnel should only leave a few milimeters (3-5 mm) wiggle room whilst the entire nipple should fit comfortably in, without much, if any, of the areola entering the flange tunnel.
Most breast pump manufacturers will offer a wide range of flange sizes so women wishing to use a breast pump should do their research, which is also advised by the Food and Drug Administration (FDA).
A lactation consultant may be able to provide help with discovering the right size flange and both nipples should be checked in case there are significant differences that call for two different sizes.
The table below summarizes the COMFY test which uses the acronym comfy to help remind of the five guidelines for proper flange fitting.
| C | Center Nipples Move Freely | The nipple should move freely in and out of the flange tunnel without pain or abrasion, leaving 3-5mm wiggle room whilst placed on nipple. |
| O | Only A Little Areola Tissues Should Be Pulled Into The Tunnel | If the flange size is too large, a significant part of the areola may be pulled into the tunnel during pumping. Contrary, if the size is too small, no areola movement will take place. Aim for something in between. |
| M | Motion Of Your Breast Is Gentle And Rhythmic | Breast should receive a moderate, natural-like stimulation for expressing breast milk, that mimics the sucking of an infant |
| F | Feels Comfortable Breast Pumping | Pumping shouldn’t be uncomfortable or cause pain, abrasion or tenderness |
| Y | Yields Well-Drained Breasts | Following pumping the breast should feel soft and light, not with areas that seem to still be full of milk |
References
Meier PP, Patel AL, Hoban R, Engstrom JL. Which breast pump for which mother: an evidence-based approach to individualizing breast pump technology. J Perinatol. 2016; 36(7):493-9.
Eglash A, Malloy ML. Breastmilk Expression and Breast Pump Technology. Clin Obstet Gynecol. 2015; 58(4):855-67.
Specialty: Neonatology
Article By: Denise Nedea
Published On: October 21, 2020 · 12:00 AM
Last Checked: October 21, 2020
Next Review: October 21, 2025