How to measure bra size: bra fit guide

How to measure your bra size

Finding the right women’s bra size can be tricky. The truth is, there’s no magical formula to give you an exact answer because 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 boobs, and so determines how snugly the bra fits around your torso. Your bra band size is the number part of a bra size, usually 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 rib cage at the level where your breast meets your ribs, parallel to the floor.

• Note the number. If it's an odd number, round it up to the nearest even one.

How to measure your bust size:

• Your bust size is a measurement around the fullest point of your boobs, and is 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, making sure it's 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 make a note.

How to find your cup size:

To calculate your approximate cup size, just 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

• 1 inch – A

• 2 inches – B

• 3 inches – C

• 4 inches – D

• 5 inches – DD

• 6 inches – E

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. Easy.

• Band size – 32 Inches

• Cup size – C

• Bra size – 32C

Why wearing the right bra size matters

The reason 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 might impact your bra size: the styles you pick, 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.

How do I know if a bra fits?

The first step to ensuring your bra fits well is making sure it's sitting on your torso correctly. This is how you should put your bra on every day, not just before bra fittings. Follow these steps:

Bands: Close the bra at the back, on the loosest hooks. Bras lose stretch over time, so you need the tighter hooks to keep it snug and make it last longer.

Straps: Pull up your straps, making sure they're sitting parallel to each other, and adjusting the tightness as needed.

Cups: Lean forward to let your boobs sit fully in the cups, scooping from either side so that nothing is being pushed under your arms.

Underwires: Pull your underwires into place, making sure no breast tissue is between the underwire and your ribs — the underwire should be sitting at the point where your boob meets your ribcage.

What are the signs that the bra doesn't fit?

The telltale signs a bra isn’t fitting right:

Straps slipping off the shoulders

Band size is too small: If your bra straps slip off your shoulders, it might mean your band size is too big. As band size increases, the placement of the straps sits further apart. You'll need to go down a band size to keep your straps from slipping. Remember: if you go down a band size, you'll 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 to hold the straps firmly in place.

Bra straps hurting shoulders

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

Bra riding up back or pinching skin

Your band size is too big: Is your bra riding up? It can cause spillage and backaches, because your boobs aren't being supported correctly. The solution? Reduce your band size.

Bra side spillage or gaps

Are your boobs spilling out at the top or sides of your cups? Or are the underwires are sitting on top of your breast tissue? The cup is probably 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 might be too large and you should size down.

Underwires hurting and digging into skin

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

If the underwires are digging into your boobs or not sitting flat against your breastbone, you might need a bigger cup size.

Middle of the bra is not lying flat

If the center of your bra isn’t sitting flat, your bra cups are probably too small. Go up a cup size and make sure the underband sits flat and securely between your boobs. If you go up a cup size, you might need to go down in band size for the best 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 it still fits correctly. Need to go down in your band size? To accommodate the change, you’d go up in your cup size. For example, 32C becomes a 34B if you go up a band size or a 30D if you go down a band size.

What kind of bra to wear after surgery?

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

What’s the best bra to wear when pregnant?

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

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

A bra riding up instead of 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 your breast tissue isn’t completely filling your cup, which may be too large. We recommend trying a smaller cup size to make sure the cup sits flush against your boobs without extra room.