Our innovative angled design and silicone flanges don't translate directly to standard flanges sizes so it usually takes trying them on with your pump to find the right size.  Also, due to elasticity issues, what looks or even measures as a certain size often turns out to be different in a flange using vacuum.  Some people use different sizes at different times of the day, some change from one size to the next to the next as their body changes over time after delivery, and others only use one size. 

That's why our flanges are available in Sets of three sizes for the price of two and include a Size Guarantee for US purchases to send any other size at no cost.  They also have a 15-day return policy for domestic orders unlike most other personal use products on the market.  

Find the Smallest Comfortable Fit with the Least Swelling

After over two decades of helping people pump, we've found the best result is usually the smallest flange that you can fit into comfortably to minimize swelling.  Most nipples will swell to fill the tunnel space but swelling puts pressure on milk ducts making it harder for the milk to flow easily.  


We recommend starting with the green Medium flange (included in both Set sizes).  Before pumping, place it against your breast and look at the amount of space between your centered nipple and the side of the tunnel.


  • Less than an eighth-inch (" or 3mm) ⇨ the green Medium flange should be the right size.
  • More than an eighth-inch (" or 3mm) ⇨ size DOWN to the pink Small silicone flange.  (Likewise, if there is more room than that in the pink Small flange, size DOWN again the blue X-Small silicone flange.)

  • Nipple doesn't fit easily into the Medium ⇨ size UP a size to the purple Large hard plastic flange.  


The next factor to look for is how much milk you're getting.  If you're getting less than with your old flanges, try the next smaller size to see if you get more.  (If you're in the silicone flanges, make sure you're deep enough in the tunnel.)


If you'd like us to check that you're using the right size, feel free to send photos and/or videos of your nipples in any flange both before and during pumping.  Jenn, our In-House Lactation Consultant, will evaluate how they look size-wise and let you know what she sees.  


If you don't have the size you need and you're in the US, just let us know and we can get it to you at no cost through our Size Guarantee.

Reviewed by Jenn Foster, MS, IBCLC, CD

February 8, 2022