If your breast pumping sessions are leaving you wincing in pain, or if your milk output seems unexpectedly low, you are not alone. The most common culprit behind uncomfortable pumping is using the wrong breast shield or flange size.
Most breast pumps come with a standard 24mm flange right out of the box, but every mother is unique. Using a flange that is too small can cause severe nipple friction, while one that is too large can pull in too much of your areola, leading to swelling and tissue damage.
Finding the right fit is the secret to comfort and efficiency. Here is everything you need to know about measuring for the perfect breast shield.
Why does my breast pump flange size matter?
Using the correct breast pump flange size prevents nipple damage, ensures maximum comfort, and helps you empty your breasts efficiently to maintain or increase your milk supply. When your flange fits properly, your nipple is drawn into the tunnel smoothly without rubbing against the sides. A poor fit not only causes intense pain but can also restrict milk ducts, leading to clogged ducts or a drop in your overall milk production.
How do I measure my nipple for a breast pump flange?
To find your flange size, measure the diameter of your nipple base using a ruler or sizing tool. Do not include your areola in this measurement. Add 2 to 3mm to your final measurement to find your ideal flange size.
Because your nipples swell slightly when you pump, timing your measurement is important:
- If you are already pumping: Pump for about 5 minutes using the default breast shield size) on a low setting to let your nipple expand, then measure.
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If you have not started pumping yet: Gently stimulate your nipple so it stands out before measuring.
Step 1: Measure your Nipple Diameter
After your nipple is swollen, measure the diameter of your nipple, starting at the base of the nipple. This does NOT include the areola. Tips: Measure in front of a mirror so you can lay your ruler perfectly.
Step 2: Select a shield size
After pumping: Add 2 to 3mm to your measured size. For example, if your nipple measures 20mm after pumping, u would want to try a 22mm shield.
How do I know if my breast pump flange is the wrong size?
Your flange is likely the wrong size if you experience pain, if your nipple rubs against the tunnel walls, or if a large portion of your areola is pulled inside the tunnel.
Here is a quick checklist to verify you have the perfect fit:
- Flange fits comfortably around your breast
- Only your nipple and a small part of your areola (or none) enter the tunnel during pumping sessions
- Your nipples are able to move freely during pumping sessions without rubbing against the side of the tunnel
- After pumping, your breasts feel soft and emptied
- Milk supply remains the same or improves
- Overall comfortable and free of pain
Can my flange size change over time?
Yes, your flange size can change throughout your breastfeeding journey due to hormone fluctuations, weight changes, and milk supply regulation.
While this guideline is a great place to start for finding the right fit, there are other factors which can impact what breast shield size is the right fit for you. To reiterate the point that every breast is different and the nipple size can change throughout your breastfeeding journey. Measurements might be different even throughout the day (you might be fuller in the morning after a few hours without pumping or feeding at night, or smaller in the evening after pumping throughout the whole day). Your measurements might change after milk supply is well-established (approximately 10 weeks postpartum),
It may take a few trials and errors to get the right one, but it will be worth it when you feel your breast-pumping sessions become more comfortable.
*Different brands may have different guidelines for selecting the right size. Do follow the guidelines provided by brands if applicable.
Essential Sizing Tools and Replacement Flanges for a Perfect Fit
Finding the right fit often requires a little trial and error, but using a printable nipple ruler can take the guesswork out of the process. Different brands offer their own specific guidelines:
- Download the Maymom printable nipple ruler to measure your size accurately.
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Use this Spectra flange sizing guide to find your perfect fit.
- Youha offers a physical silicone nipple ruler you can keep in your pumping bag, Shop Here
If your standard 24mm flange is too big, you do not necessarily need to buy a whole new setup. You can easily size down using Maymom silicone sizing inserts or opt for replacement flanges which are highly popular for moms needing smaller, more customized fits.
At Pupsik, we carry a massive variety of replacement breast shields, flanges, and sizing inserts from top brands to help you achieve the perfect fit.
Ready to upgrade your pumping experience?
Shop our full collection of breast pump accessories and flanges here!