Find your flange size in under a minute

Measure your nipple diameter, tell us your pump brand, and we'll estimate your starting flange size — plus how to check the fit once you're pumping.

Based on our full flange sizing guide, reviewed against Cleveland Clinic and manufacturer guidance.

How to measure first

1 Stimulate briefly Roll the nipple gently for a few seconds so it's everted — not right after pumping.

2 Measure the base Straight across the widest point, in millimeters. Nipple only — not the areola.

3 Check both sides Your two nipples can differ — measure each one separately.

Measure straight across the base of the nipple only — the shaded areola isn't part of the measurement.

Your measurement

When did you measure?

Neutral / before pumping Recommended — nipple at rest

Right after pumping Nipple already swollen

Nipple diameter

8 mm34 mm

Pump brand (optional)

Read the full flange sizing guideSize chart, inserts, and troubleshooting fit → How to center and seat your flangePositioning tips once you have your size → Browse pump reviewsCompare flange options across brands →

This tool gives an estimated starting size based on manufacturer sizing charts and published flange-fit guidance. It isn't medical advice and isn't affiliated with any pump brand named here. Nipple size can change over time, and fit is confirmed by watching the pump in action — not by measurement alone. If pumping is painful or your nipple changes color or shape, stop and check in with a lactation consultant (IBCLC).