How to measure bra size: bra fit guide

How to measure your bra size

Finding the right women’s bra size can seem tricky. The truth is, there’s no magical formula that will give you an exact answer as everyone’s body is different, but we do have a process for finding your starting size to make bra fitting faster and easier.

How to measure your bra band size:

Your bra band size is the measurement of your ribcage in inches. This directly relates to the underband of your bra, which provides the main support for your breasts, and therefore determines how snugly the bra fits around your torso. Your bra band size is the number part of a bra size, usually ranging from 28 to 42. To measure:

• Stand in front of your mirror with a soft measuring tape, ideally without a bra on.

• Wrap the measuring tape around your ribcage at the level where your breast meets your ribs, parallel to the floor.

• Note the number. If it is odd, round it up to the nearest even number.

How to measure your bust size:

• Your bust size is a measurement around the fullest point of your bust and will be the first step to understanding the volume of your cups. Make sure your measuring tape is in inches.

• Stand in front of your mirror with a soft measuring tape, wearing either a non-padded bra or no bra at all.

• Wrap the measuring tape around the fullest point of your bust, ensuring it is straight around, parallel to the floor.

• Make sure the tape is snug, but not pulled tight or digging in, and note the number on the tape.

• Round this measurement to the nearest whole number and take note of it.

How to find your cup size:

To calculate your approximate cup size, simply subtract your band and bust size. Each inch of difference between your measurements correlates to a lettered cup size, as below.

Cup size measurement chart

• 0 inches – AA cup

• 1 inch – A cup

• 2 inches – B cup

• 3 inches – C cup

• 4 inches – D cup

• 5 inches – DD cup

• 6 inches – E cup

Example: If your bust size is 35 inches and your band size is 32 inches, you have a three inch difference, meaning you’re a cup size C. Your overall bra size is then a 32C. Simple.

• Band size – 32 Inches

• Cup size – C

• Bra size – 32C

Why wearing the right bra size matters

The reason that fitting a bra is so important is because these measurements don’t completely account for how breast tissue is distributed on each person’s body. Other things that may impact your bra size are the types of bra styles you choose, the materials of the bra and even the brand. We always recommend trying on and testing the fit of each bra you buy, to make sure you’re comfortable and correctly supported. Read our guide on the most comfortable bras to find a style for everyday outfits and evening looks.

How to know if a bra fits?

The first step to ensuring your bra fits correctly is making sure that it is sitting on your torso properly. This is how you should put your bra on every day, not just ahead of bra fittings! Follow these steps:

Bands: Fasten the bra at the rear, on the loosest hooks. Bras lose elasticity over time, so you need the tighter hooks to keep it snug and provide longevity.

Straps: Pull up your straps, ensuring they are sat parallel from each other, adjusting the tightness as needed.

Cups: Lean forward to allow your breast tissue to sit fully in the cups, scooping from either side so that no tissue is being pushed under your arms.

Underwires: Pull your underwires into place, ensuring that no breast tissue is between the underwire and your ribs — the underwire should be sat at the point where your breast meets your ribcage.

What are the signs that the bra is not fitting?

Here are the tell-tale signs that a bra isn’t fitting right:

Bra straps slipping off the shoulders

Band size is too small: If your bra straps slip off your shoulders this may indicate that your band size is too big. As band size increases, the placement of the straps sits further apart. You will need to go down a band size to prevent your straps from slipping. Remember, if you go down a band size, you will need to go up a cup size.

Narrow shoulders: Falling bra straps may also mean you have sloping shoulders, so pick bras with wide straps or with a racer back design that hold the straps firmly in place. We have lots of options with wide straps or racerback designs, from bralettes, wireless bras, plunge bra options to full coverage bras.

Bra straps hurt shoulders

If too tight, adjust the straps so they fit without causing red marks, but not loose enough that they fall down your shoulder.

Bra riding up back or pinching skin

Your band size is too big: If your bra is riding up, this can cause spillage and back aches as your bust is not correctly supported. The solution? Reduce your band size.

Bra side spillage or gaps

If you’re finding that your breast tissue is spilling out at the top or sides of your cups, or that the underwires are sitting on top of breast tissue, it’s likely that the cup is too small and you should size up.

If your cup is gaping at the top and side of your bra or the material is wrinkling, your cup may be too large and you should size down.

Underwires hurting and digging into skin

If you’re finding your underwires uncomfortable, you may need to try a smaller cup size.

If your underwires are digging into your breasts or not sitting flat to your sternum, you may need a bigger cup size.

Middle of the bra is not lying flat

If the centre of your bra isn’t sitting flat, it’s likely that your bra cups are too small. Go up a cup size and make sure that the underband sits flat and securely between the breast tissues. If you go up a cup size, you may need to go down in band size for the best fit. 

Read our guide on the best bras for small busts to find your perfect fit.

FAQs

What is a sister bra size?

Sister sizes are two different bra sizes that have the same cup capacity, but a different band size. If you change your band size, you need to adjust the cup size too, so that it still fits correctly. If you need to go down in your band size, to accommodate this change, you’d go up in your cup size. For example, 32C becomes a 34B if you increase the band size or a 30D if you decrease the band size.

What kind of bra to wear after surgery?

The best post-surgery bras are designed to provide support and comfort to those who have previously undergone a procedure. They differ from regular bras in that they have a front fastening, wider straps, more coverage, pockets for prosthesis and softer fabrics — designed to be gentle on delicate skin. If you’re measuring for a post-surgical bra before your operation, we recommend one to two band sizes larger than you normally would, to accommodate any potential post-surgery swelling.

What’s the best bra to wear while pregnant?

Maternity bras feature wide, comfortable straps to cater to your bodily changes during pregnancy. If the straps feature clips, it is a nursing bra, designed for ease when breastfeeding. Most maternity bras also come with extra hook-and-eye loops to allow you to adjust the bra more effectively as your size expands during pregnancy and reduces after birth.

Why does my bra ride up when I lift my arms?

A bra riding up and not staying in place is a sign that your underband is too loose. Try sizing down on your underband to make sure it can comfortably hold the bra in place against your body. It’s also worth checking that your straps aren’t too tight.

Why do my bra cups wrinkle?

Wrinkled cups are a sign that your breast tissue isn’t completely filling your cup as it may be too large, we recommend trying a smaller cup size to make sure that the cup sits flush against your breasts without extra room.