Flange Sizing & Nipple Measurement Guide

Getting your flange size right means better milk output, less discomfort, and no rubbing — here's how to find yours.

What You'll Need

1

Nipple ruler

Purpose-made for this measurement

2

ProCircle

A simple sizing tool available at any stationery shop — easy for everyone to get hold of

Before You Start

  • Measure before breastfeeding or pumping
  • Make sure your nipple is in a natural, relaxed state
  • Do not include the areola (the dark area around the nipple)

Step-by-Step Instructions

1

Use a measuring tool

Use a ProCircle or nipple ruler to find your nipple diameter, in mm.

2

Position correctly

Place the measuring holes over your nipple and find the size that fits snugly, without squeezing.

3

Measure only the nipple

Make sure you're measuring only the nipple tip, not the surrounding areola.

4

Note your size

Record the size in millimeters (mm) — you'll use this in the chart below.

Then add 2–4mm to your measurement — this leaves enough room for slight expansion during pumping without being too loose.

Find Your Size

Nipple Diameter Recommended Flange
10–11mm 13mm
12–13mm 15mm
14–15mm 17mm
16–17mm 19mm
18–19mm 21mm
20–22mm 24mm

Flat or Inverted Nipples

If your nipple doesn't protrude much, or draws inward instead of out, standard measuring can be tricky to get right. A few things that help:

1

Try the pinch test first

Gently compress the areola about an inch behind the nipple. If it stands out, it's likely flat rather than truly inverted, and will usually draw out further once pumping begins.

2

Measure after gentle stimulation

Rolling the nipple briefly between your fingers before measuring gives a more realistic size, since suction will draw it out further than its fully resting state.

3

Expect to size down slightly

Many moms with flat or inverted nipples find a slightly smaller flange helps create the seal needed to draw the nipple out and maintain suction.

4

Give it a few sessions

It's common to take a little longer to fully draw out with each session at first — this usually improves with regular pumping.

Flat and inverted nipples vary a lot from person to person, so if you're still unsure after trying this, it's worth sending us your measurement (see below) or checking in with a lactation consultant for a personalized fit.

Know Your Fit

✓

Correct Fit

  • Nipple moves freely, centered in the tunnel
  • No pain, rubbing, or discomfort during pumping
  • Steady, comfortable milk flow
–

Too Small

  • Nipple rubs or drags against the tunnel walls
  • Pain, redness, or the nipple turns white / looks pinched
  • Lower milk output than expected
+

Too Big

  • Too much areola gets pulled into the tunnel
  • Nipple moves around a lot inside the flange
  • Reduced suction or lower milk output

If Unsure, You Can Send Us Your Measurement for Guidance

It's normal for your size to change over the first few weeks of pumping, or between breasts. If you're between two sizes, it's usually better to size up slightly rather than down.

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