For maximum comfort and pumping efficiency, Medela offers five breast shield sizes. This guide is a starting point to help determine your optimal size.

Reasons to try a new size

  • Does your nipple rub the tunnel sides to the point of causing discomfort?
  • Do you see excessive areola being pulled into the tunnel?
  • Do you see any redness?
  • Is your nipple or areola turning white?
  • Do you feel unexpressed milk after breast milk pumping?

If you answered “YES” to any of these questions, consider trying a new size by following the measuring instructions below.

If you are still unsure that you selected the right breast shield size, contact a lactation consultant or breastfeeding specialist.

Understanding Medela’s PersonalFit sizing

Step 1

Using a ruler or measuring tape measure the diameter of your nipple at base (across middle) in millimeters (mm). Do not include areola.

Step 2

Based on your breast measurement, determine your PersonalFit nipple shield size. Example: If your nipple size measures 17 mm in diameter, the recommended PersonalFit breast shield size is
21 mm.

Test your breast shield size

  • Start with the 24 mm that came with your pump, or the size determined by measuring.
  • Center the nipple and gently hold the breast shield against your breast.
  • Adjust for Maximum Comfort VacuumTM to achieve optimum suction level.
  • Refer to the images below while pumping in the expression phase (after the stimulation phase).