Nursing Bras: How To Measure Your Bra Size

Ensuring correct nursing bra sizing before buying is key for having a more comfortable breastfeeding experience! See our how-to guide below:

Most women notice that their regular bra begins to feel tight sometime around the second trimester of their pregnancy. This is a good indicator that it’s time to purchase some maternity and nursing bras as you prepare for the rest of your pregnancy and then breastfeeding. That's why it's important to know how to measure your bra size.

Nursing bra sizing doesn’t differ from sizing for regular bras, though it is sometimes recommended to purchase your nursing bras in a cup size or two up to account for fuller breasts during pregnancy and while breastfeeding.

The Importance of the Correct Nursing Bra Size

Comfort and functionality are important features to look for in a nursing bra, especially as your body changes. Ensuring that you buy the correct nursing bra size is key for optimizing each bra's design and features. While every woman's body is different, taking extra precautions by steering clear of things like lace and underwire in maternity bras can help alleviate discomfort and aggravation while your breasts are growing - and producing milk for your new baby.

Approximately 80% of all women wear the wrong bra size. Seventy percent wear bras that are too small and 10% wear bras that are too large. This may adversely affect your breast milk supply, as it is widely believed that nursing bras that are too tight or have underwire that digs into your breast tissue could block one or more milk ducts. A blocked milk duct can be troublesome and eventually lead to infection or mastitis if not treated right away by a healthcare professional. Proper nursing bra sizing can be quite easy to measure if you know how to measure your bra size at home - just use the directions below:

How to Measure Bra Size Using Our Nursing Bra Sizing Chart

Measuring yourself to determine your bra size will give you a starting point before you begin trying on nursing bras. You'll need a few things handy to get started:

What You'll Need to Measure Your Bra Size

  • Measuring tape
  • Blank paper
  • Pen
  • A non-padded bra reflecting your true shape
  • A full-length or bathroom mirror

Once you're ready to begin measuring, follow these steps to figure out your current bra size:

Find Your Rib Measurement

  • Pull the measuring tape around your back and beneath your armpits. The measuring tape should lie above your breast tissue.
  • While looking in the mirror, ensure the measuring tape is parallel to the floor around your back. Confirm that there are no fingers under the tape and exhale.
  • Write down the measurement that you see. If you are between sizes, round up or down to the nearest full, even number (such as 34, 36, or 38). This is your rib band measurement.

Measure Your Nursing Bra Cup Size

  • Adjust the tape so it is still wrapped around you, but now measures around the fullest part of your breasts.
  • Hold the end of the measuring tape at the side of your chest and grab both ends of the tape in one hand.
  • Use your free hand to press the measuring tape between your breasts and into your chest.
  • Write down the measurement that you see. Note that this will likely be a larger measurement than your rib band but should provide an accurate cup size.

Nursing Bra Size Chart

Subtract your rib band measurement from your cup size measurement - for example, 36 - 32. The difference (4) should be matched with the corresponding letter in the nursing bra size chart below:

0 1 2 3 4 5 6 7


Your nursing bra size is your original rib band measurement (36) with the letter matching your cup size (D), so our example bra size would be 36D.

Finding the Best Nursing Bras

Once you find the perfect fit, you may want to try our Keep Cool™ Ultra Bra, with six integrated breathing zones and quick dry technology to keep you feeling cool and comfortable. This maternity and nursing bra also features fully fold-down cups to maximize skin-to-skin contact when feeding your baby. 

Medela's maternity and nursing apparel was designed to meet your unique needs 24 hours a day, 365 days a year. Our maternity and nursing bras naturally adapt to your changing shape and keep you comfortable while conveniently allowing you to pump or nurse whenever needed. Throughout each step of your breastfeeding journey, Medela is proud to provide exceptional fit, comfort, and functionality to parents around the world.

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