Whether you're a first-time pumper or you've been using a breast pump for quite some time, proper flange size is key to comfortable and successful pumping. Incorrect flange size can affect milk production, cause nipple pain or damage and result in clogged milk ducts. It can also interfere with the pumping process and cause nipple rubbing, skin irritation or areola entrance into the flange tunnel. Luckily, it's pretty easy to determine the right flange size for your nipple and areola size by measuring your nipple before and after pumping or after consulting with a lactation specialist.
To measure your nipple for flange size, use a ruler or fabric measuring tape and mark the nipple's diameter at its base, making sure to exclude the areola. Flange sizes are typically measured in millimeters (hint: 1 centimeter equals 10 mm). Once you've got your measurement, add 3-4 mm to that number to get the correct flange size.
You'll want to measure your nipple before and after each pumping session, as your nipple size will likely change throughout breastfeeding/pumping. You should also be mindful of nipple elasticity, which is the stretching of the nipple and areola to accommodate a baby. If you notice your nipple is stretching beyond the halfway point of your flange tunnel or the top of your areola is entering the flange, then you need to increase your flange size. To ensure the best fit, it's also recommended to consult with a qualified IBCLC for assistance determining the ideal flange size for your unique nipple and areola shape.