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How to Choose Your Breast Pump Shield Size

Breast shield sizing guide

How do I measure my nipple for a breast pump flange?

Measure your nipple at its base, not the areola, in mm; your nipple diameter, not your breast size, decides the flange size. 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.

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

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 in millimetres, as each side may need a different size.

3

Confirm while pumping

Use your pump’s size chart as a starting point, then check comfort and nipple movement while pumping.

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 (mm) Bloome insert
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.

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

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.

Common questions

Breast Pump Flange Size FAQ

What if I measured my nipple incorrectly?

Measure again at the nipple base in millimetres, without including the areola, and compare the result with the chart for your pump. Treat the suggested size as a starting point and check how it fits during use; if you are unsure, ask for help with a fit check.

What if my nipples need different flange sizes?

Measure each nipple separately and use the suggested size for each side as your starting point. You do not need to use the same insert or breast shield size on both breasts.

Should I measure during pregnancy or after birth?

A measurement during pregnancy is only a starting point, as your size may change after birth. Recheck when you begin pumping after birth and whenever your usual fit changes.

Should pumping hurt if the flange size is correct?

No. Pain does not confirm a sizing problem on its own, and suction and positioning also need checking. If pumping remains painful after checking the fit and suction setting, stop and speak with a midwife, lactation consultant or another qualified healthcare professional.

Which inserts fit the Bloome wearable breast pump?

Bloome uses a 25 mm cushion with compatible silicone inserts in 15, 17, 19 and 21 mm sizes. Use the Bloome chart on this page as a starting point, then check the fit during pumping.

Further Guidance and Support

For help checking your fit, you can use Lola&Lykke’s free expert consultations or speak with your midwife or a lactation consultant.

This guide provides general product-sizing information and does not replace personalised advice from a qualified healthcare professional; the size charts are starting points, not a diagnosis or a guarantee of fit.

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