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How Bras Should Fit (and How to Know If Yours Does)

We talk about bras around here a lot. It’s one of my all-time favorite topics of discussion and one area I can’t get enough of—truly!

Getting the proper fit is the *most* essential part of wearing a bra. Nobody wants to wear a bra that makes them feel like a lopsided mess, nor do they want to feel like their bra could support the hoover dam. Ok, well, maybe some people want that. 🤣

If you remember nothing else about bra fitting, remember this: Your bra band should be doing 80 to 90% of the work, and the straps only do the light lifting, carrying 10% to 20% of the total weight. When the band is doing most of the work, you’re getting support from 360º around the body as opposed to a 90ª up and down pull coming from the straps doing all the hard work.

A woman's shoulders showing harsh red indentations from bra straps digging in.

Another great point of a good-fitting bra band is that it will help you avoid developing bra-strap syndrome, aka visible dents created from wearing bras with loose bands and straps that dig in.

Before we tell you how to fit yourself into a new bra… Let’s go over how bras should fit to make sure you’re not already wearing the correct size. Here’s how to do a fit check in 6 easy steps:

How can you tell if you’re wearing the incorrect bra size?

A bra band riding up a woman's back because it's too loose.

1. Your band is riding up in the back. A well-fitting bra should fit firmly around your body, letting the band do most of the work to support your breast tissue. The band should sit straight across your back. If it’s riding up, that’s a telltale sign that your band is too large. Try going down a band size.

A bra band being pulled far away from the wearer's body because it's too loose.

2. You can pull the band away far away from your back. You should be able to pull the bra band away from your back no more than an inch…*maybe* two, depending on how tight or comfortable you like to wear your bras. If you can pull it further, your band is too easy and not snug enough to support you. Try going down a band size.

Breasts bulging out of a bra because the cup size is too small.

3. Your breasts are bulging out of the cup. The cups should encapsulate all the tissue without spilling out over the edges at the armhole or neckline. Nobody wants a double or quad boob. Try going up a cup size.

Bra cups gaping away from the wearer's body because the cup size is too large.

4. You’re not filling up the entire cup. There should be zero to minimal gapping between the cup and the body, either above or below. If the cup stands away from your body, try going down a cup size.

The gore of a bra not sitting flush to the body because the bra band is too big.

5. The gore is not sitting flush against you. The center front of the bra should tack against your sternum to feel the most supported and contained. If it’s floating away from your center front, try going up a cup size and down a band size if your bra feels too loose around.

Underwire sitting on the wearer's breast tissue because the cup size is too small.

6. The underwire is sitting on your breast tissue. The wires should sit on the flattest part of the upper body around your ribcage, following along the underboob shape. If the wire is sitting on breast tissue, your bra is probably a cup size too small, and you may need a wider wire. Try going up a cup size.

How’d you do? If it turns out that you might need a new bra, let’s go over how to ensure you’re starting from the right bra size.

We’ll start by taking a few key measurements, and once we’ve got those, we can show you how to find the two closest sister sizes to your size.

How to measure yourself for your correct bra size:

1. Measure your underbust.

  1. Begin by measuring your underbust area snuggly around the ribcage with a soft measuring tape.

  2. With the tape snug against your body, but not so tight you can hardly breathe, wrap it around your bra line just under your breast tissue.

  3. Don’t forget it should sit straight across your back, parallel to the floor. Record the number you get in inches. This is how we find your band size.

    1. If it's an even number, start with that as your band size.

    2. If it's odd and you prefer a more comfy, looser fit, start with your band size as the next even number up.

    3. If it's odd and you prefer a more snug, supportive fit, round down to the next even number for your band size.

  4. Example: Your snug underbust measures 31”, but we’ll round up to 32” for our band size. For your more snug sister size, you’d round down to 30” for your band size.

2. Measure your fullest bust.

  1. Next, measure around the fullest part of your bust.

  2. The tape should be horizontal to the floor, and ensure you keep it straight and around the fullest part. The tape measure should be snug but not so tight that it changes or distorts your cup shape.

  3. Record this measurement in inches. This measurement helps identify your cup size.

  4. Example: Your fullest bust measures in a 36” band.

3. Subtract your underbust from your fullest bust.

  1. Lastly, subtract your underbust measurement from your overbust measurement to get your cup size.

    1. The cup is based on the system that 1” of difference is a cup size.

    2. So if you had a difference of 1”, you’d be an A cup. 2”, you’d be a B cup. If you had a difference of 5” you’d be a DD(US) or E(UK) cup.

  2. Example: Take measurement B and subtract measurement A to find your cup. 36” - 31” = difference, which would mean a 32DD (rounding the band up) or a 30DDD (rounding the band down) would be a good starting point for you.

Bra size chart

4. Consult a bra sizing matrix.

  1. Using your measurement, the chart will guide you to what size band and cup are the closest fitting sizes to you. Remember that there is no “right” or “wrong” size for bras; the most important thing is that the fit is comfortable and supportive for you.

5. Try on multiple sizes.

  1. Based on the size chart, you could fall into different related sizes called sister sizes. For this reason, it’s always a good idea to try on different sizes to get an idea of what fits best for you. You want to ensure it provides enough coverage without being too tight or loose.

    1. Not sure how to figure out what you like best? Try on your bra sizes nearest sister sizes by going up one band size while going down a cup size or going down a band size and up a cup size. IE. if you're a 34DD normally, try a 36D and a 32DDD as well as your normal size. You might be surprised!

Finding the perfect bra size can be a challenge, but it doesn't have to be. By taking a few measurements, consulting a bra size chart, and trying a few different sizes, you're sure to find a fit that works for you.

If you're still feeling unsure about your bra size or you want some help finding one, we suggest visiting a professional bra fitter in person. Do a quick Google search to find one near you. If you’re in the Connecticut area, I highly recommend checking out Filly Rose, owned and operated by a friend of mine, Elizabeth Basile. Having a well-fitting and comfortable bra will do wonders for your health and confidence!

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