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How to Choose Your Breast Pump Shield Size

Breast shield sizing guide

Find Your Breast Pump Fit

The right breast shield or insert should help your nipple move freely while maintaining a comfortable seal. A better fit can make pumping feel more comfortable and support effective milk removal.

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Pumping should not hurt. Your size can also change during pregnancy, postpartum and breastfeeding, and you may need a different size for each breast.

Start here

Measure Your Nipple

Measure the diameter of the nipple at its base in millimetres. Measure the nipple itself, without including the surrounding areola. For the most useful starting measurement, check shortly before pumping or feeding.

1

Measure the base

Place a ruler or nipple measuring card across the widest part of the nipple base.

2

Check both sides

Measure each nipple separately. It is completely normal for them to require different sizes.

3

Confirm while pumping

The measurement gives you a starting point. Comfort and nipple movement confirm the final fit.

How to measure nipple diameter when choosing a breast shield size

Choose your pump

Breast Shield and Insert Size Charts

Lola&Lykke pumps use different fitting systems. Bloome uses a soft 25 mm cushion with optional silicone inserts, while the Smart Electric Breast Pump uses interchangeable breast shields.

Bloome Wearable

Silicone insert sizing

Nipple diameter Suggested size
11–13 mm 15 mm insert
13–15 mm 17 mm insert
15–17 mm 19 mm insert
17–20 mm 21 mm insert
21 mm or more 25 mm cushion

Bloome includes a 25 mm cushion and 15, 17, 19 and 21 mm silicone inserts.

Smart Electric

Breast shield sizing

Nipple diameter Suggested shield
Up to 17 mm 21 mm shield
17–20 mm 24 mm shield
20–25 mm 27 mm shield

These measurements are a starting point. Breast tissue and skin elasticity also affect how a breast shield fits in use.

Fit check

What a Good Fit Looks Like

Centre your nipple in the tunnel before starting. Begin with a low suction level and increase it only while pumping remains comfortable.

Correct and incorrect breast shield fit during pumping
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A good fit

  • Your nipple is centred in the tunnel.
  • It moves freely without rubbing against the sides.
  • Only a small amount of areola is drawn into the tunnel.
  • Pumping feels comfortable throughout the session.
  • Your breast feels softer after pumping.
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Recheck your size if

  • Your nipple rubs painfully against the tunnel.
  • A large amount of areola is pulled inside.
  • You notice pinching, swelling, redness or blanching.
  • Your nipple cannot move freely.
  • Your breast still feels unusually full after pumping.

Keep the pressure gentle. Do not press the shield firmly into your breast, as excessive pressure can restrict milk flow. Higher suction is not necessarily more effective. Choose the highest setting that remains completely comfortable.

Worth remembering

Your Fit May Change

Hormonal changes, swelling and regular pumping can affect nipple size over time. Recheck your measurements if pumping becomes uncomfortable, your nipple movement changes or your usual shield no longer forms a reliable seal.

If pumping remains painful after checking the fit and suction setting, stop and speak with a midwife, lactation consultant or another qualified healthcare professional.

Find the Right Size for Your Pump

Shop breast shields for the Smart Electric Breast Pump, silicone inserts for Bloome or explore all breastfeeding accessories.

Smart Electric Breast Shields Bloome Silicone Inserts View All Accessories