11 Expert Tips for Finding the Right Bra Size and Fit

Did you know you have more than one bra size?
a woman shopping for bras
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For many people, bra shopping falls somewhere on the emotional scale between flat-out disappointing and totally traumatic, and the same could be said for the actual wearing of said bras. Many women are wearing uncomfortable bras that dig into their skin, slip off their shoulders, and create awkward spillage situations—and then rip them off their bodies the minute they get home. A lot of this can be traced back to the lingerie store: If you don’t know how to find the right bra (or even the right bra size!), you’re not going to get one that’s best for you. Put simply, women aren’t getting the support they need to get the support they need.

To make sure you get the most out of this experience, I reached out to three stylists and bra fitting experts who gave a detailed rundown of tips you should consider when buying a bra. Their advice, from breaking down bra components to telltale signs when your bra is too small or too big, is useful for women of all ages and sizes. Read on for 11 things every bra-wearing person should know.

1. Most of the support comes from the band.

Cups hold the breasts in place, but the band is responsible for about 90 percent of the actual support (strapless bras exist for a reason). So while the straps may seem like they’re there to hold up your bust, they are really there to help keep your cup flush with your body and to shape your breast. In fact, if your band and cup both fit well, you should be able to slip off your straps and take a few steps while your bra stays in place, bra expert Kimmay Caldwell from Hurray Kimmay tells SELF.

2. You need to know your size and your “sister size.”

Just like with other notoriously difficult-to-shop-for items, like jeans, there’s a wide variation in how bras of the same size will fit from brand to brand, even from one style to another. That’s why experts say women should know both their true size and their sister sizes. If a bra doesn’t fit in your regular size, it might work in your sister size.

The rule of thumb is as follows: If you go up in the band, go down in the cup and vice versa. For example, a 32C could possibly fit a 30D or a 34B. If you’re a 34C, you might find bras that fit better in a 36B or a 32D.

Knowing your sister size is useful to accommodate for size differences between brands. It is also a good resource if your “real size” is hard to shop for. People with smaller bands and large cup sizes, or larger bands and smaller cup sizes, will benefit most from sister sizing.

3. There’s an equation for figuring out your band and cup size.

Your bra size is a ratio that combines the measurements of your cup (letters AA-M) and band size (numbered 28-44). It’s a really good idea for any woman to get a professional bra fitting at a boutique—you might be surprised what a bra expert will tell you, such as you’ve been wearing the wrong size your whole adult life. You can also measure yourself at home with some tape.

To measure at home, you’ll need two measurements: around your back and under your bust for your band size, and around your back over your nipples for your cup size. You’ll then subtract the difference. For example, if your bust measures 35 inches and your under-bust (or rib cage) 32 inches, you’ll be a 32C because 35 minus 32 equals 3, and that number corresponds to the letter “C” in the alphabet.

4. If your breasts are two different sizes, round up.

It’s totally normal and really common to have one breast that is bigger than the other. If the difference is significant enough that it makes bra shopping even more complicated than it already is, Cora Harrington, lingerie expert and author of the upcoming book In Intimate Detail: How to Choose, Wear, and Love Lingerie, suggests fitting to the larger breast. If you want, you can even out the appearance by adding a bra cutlet to the smaller breast, or getting a bra with removable pads and taking them out on the big side.

5. If bras straps are digging into your shoulders, it could mean your cups are too small...

If your breasts are spilling out around the edges of the cup, they might be putting a lot of extra weight on the straps—and you may find yourself pulling the straps taut to hold them in check. Either way, your shoulders would probably benefit from larger cups.

6. ...or your band is too big.

Your straps could also be digging into your shoulders if your band is too loose, making it so your straps are doing all the work. Take a look behind you in the mirror: If your straps are pulled so tight that they're yanking your strap up, it's probably too big or is too stretched out to do its job.

7. If your straps are slipping, it could be one of a few signs that your cups are too big.

Another tell is if the center gore, or the center panel on the front your bra between the cups, is floating away. It should lay flat against the middle of your chest. And obviously, if the cups are gapping because your breasts are not filling them all the way, you may want to go down a cup size.

8. The band should be snug, not suffocating or loose.

When you’ve got the right band size, you should be able to fit your finger between your back and the strap with only about an inch of stretch. Your band is too small if the underwire is squeezing or digging in your breast tissue. But looser is not better when it comes to support. Caldwell notes that most people think loose means more comfort (think: caftans or sweatpants), but that doesn’t work for bras. Remember that the band is what accomplishes most of the holding-up of the breasts, so a loose band that rides up between your shoulder blades will not provide the support you need and leave you less comfortable in the long run.

To keep your band fitting as well as possible for as long as possible, Caldwell advises you start off by wearing your bra on the loosest hook, so when you bra starts to feel worn out, you can use the second and then third hook for more grip.

9. “Full bust,” “full figure,” and “plus size” mean different things.

According to 2016 a survey of 2,000 shoppers by lingerie retailer Rigby & Peller, the most popular sizes for women across the country is between 32DDD and 34G (that’s 32E and 34F in UK bra sizing). More brands offer bras in a range of larger sizing, sometimes labeled as plus size, full bust, or full figure. They all mean slightly different things:

-Women with a small band and large cup size are considered full bust. That includes sizes of a DD cup or larger and a 36 band or less. Full bust sizes includes sizes like 28G, 30F, 32E, and 34H.

-Plus size for bras have a band size of 38 or larger.

-Full figure encompasses sizes DD+ with a 38 or larger band. All full figure bras are also plus size, but not all plus size bras are full figure: A 38F would be considered full figure and plus size, but a 40B would be just plus size.

10. Different bra styles and materials serve different purposes.

Ideally, your bra options should complement your wardrobe. You want styles that are versatile, but comfortable enough to take you from day to night. You also want multiple bras so that you don’t stretch a bra out too fast. The experts I spoke to agreed that everyone should have at least:

-Two traditional-style bras, like a smooth T-shirt bra in your skin tone, or in black, which would cover about 70 to 80 percent of your wardrobe.

-A sports bra that minimizes bounce during physical activities, but doesn’t impede your performance. You might want different bras with different levels of support for high impact activities like running versus yoga or Pilates. (Plus, if you work out a lot, you’ll want several so that you’re not constantly washing them.)

-A convertible bra that can be strapless, racerback, halter, or criss-cross for tops with “unusual” necklines and for formal occasions.

-A non-underwire bra or bralette you can wear traveling or lounging. Just make sure you can adjust the straps to get the best fit.

The fabric and technology of a bra is also important to take into consideration, Jenny Altman, fashion stylist and lingerie expert from the blog I Love a Good, tells SELF. “That’s why it’s important to ask yourself a few questions when picking a fabric: What do you need that bra to do for you? Does it wick away sweat? Do you want a lace detail? Or do you have sensitive skin and need a softer fabric?”

11. Bras don’t last forever—even your favorite one has to be replaced when it no longer gives you the support it used to.

The experts I spoke to said that depending on your size, how well you take care of your bras (never throw them in dryer!), and how many you have on rotation, a good, basic bra should last about a year. Washing them gently by hand (after typically after three to four wears) and rotating your bras (that is, not wearing the same one multiple days in a row) will also help keep the bands from stretching out too quickly. But no matter what you do, you’ll have to say goodbye at some point, so keep a lookout for signs, like the band creeping up your back, telling you it’s time to go bra shopping.