Bras: most ladies wear ‘em. But did you know that lots of women—perhaps even the majority—are wearing the incorrect bra size? This can cause back pain, discomfort from poking wires, and poor shaping of the breasts. So how do you get into the right size?
In this article, we’ll provide your complete bra size guide. We’ll discuss why incorrect bra sizes are so prevalent, key indicators of bra fit, a complete step-by-step guide to measuring your size, and some final advice and troubleshooting on bra sizing.
Why Are So Many Women Wearing the Wrong Bra Size?
So why are so many women in the wrong bra sizes? The most prevalent error is wearing too large of a band and too small of a cup. Why does this happen so often? There are a variety of factors at play, but here are three major reasons:
You’re Not Sure How A Bra Should Fit
Bras are actually quite complicated in terms of their construction, and bodies and breasts have basically infinite variety. It’s not too surprising, then, that many folks aren’t actually 100% clear on how a bra should actually fit.
You might think that if it’s not obviously the wrong size it’s probably fine. But wearing an incorrect bra can cause digging, discomfort, poor support, back pain, awkward fit, and visible bra lines. I’ll go into more detail on what makes for a good fit later on, but here are some brief guidelines on correct fit:
- Most of the support comes from the band, not the straps, so having a tight enough band to provide support is essential.
- A band size that is too loose can cause as much digging, puckering, and visible lines as a band that is too tight. Loose bands ride up into the flesh of your upper back/shoulders, which creates lines.
- Most women know there shouldn’t be breast tissue spilling up over the top of the cup (causing the dreaded quad-boob), but you may not know that containing the breast tissue along the sides of your body is just as important. Cups that are too small may appear to fit in the front but actually dig into the side of the breast, causing discomfort and poor support.
Your Breasts Are Changing Faster Than Your Bra
Breast size changes subtly over time for many reasons: weight gain or loss, increasing or decreasing muscle tone, hormonal changes, and so on. So your bra size from two years ago may well not be your bra size now. This is totally normal, but it does mean that you should probably re-measure about once a year
A related issue is that bras do stretch out and change over time, so even if you are the same size, your bra might not be. You can delay a bra’s demise through proper care (hand-washing, using lingerie wash, cold water, air-drying) but you can’t forestall it completely. Thus, if you haven’t gotten a new bra in a long time you might be having fit issues even if your size hasn’t changed.
Sub-Par Professional Bra Fittings
You may think, but aha, I’ve been professionally fitted! There is no way I am wearing the wrong size.
Unfortunately, think again. Fitters at chain stores, particularly those that only sell one brand, are often not going to fit you correctly. Why? Because they may only carry restricted size ranges and they want you to buy a bra at their store. You might be a 30E, but if the store doesn’t carry that size the salesperson may steer you towards a 32D, which probably won’t have as good of a fit. Some salespeople might not even know how to measure bra size accurately, depending on the company’s training programs and their own bra fitting biases.
Many women don’t know how to measure for a bra, so they rely on professional fitters. In terms of professional fitters, your best bet for an accurate bra fitting are those at upscale department stores and lingerie boutiques that sell multiple bra brands. They will be the most reliable about steering you towards the right size overall, especially if they carry or can order extended size ranges, because they won’t be relying on you falling in a particular bra size range to make a sale.
And of course, even the best professional fitter can be wrong. Ultimately, you’re the best arbiter of your own bra size because you’re the one who is going to be wearing it day in and day out.
How Should a Bra REALLY Fit?
Here are some key indicators of a good bra fit:
Most Support Comes From the Band
Most of the support in a bra comes from the band, not the cups or straps. If you slip the straps down from your shoulders and the bra immediately starts to slip down your body, or your breasts feel totally unsupported, you are probably in a band that is too loose. Our guide on how to measure bra size below will get you the right band size.
Adjusted Straps Don’t Slip Down
Ideally, with a proper bra fitting, the straps of your bra should not slip down off of your shoulders if the bra is the proper size and the straps are adjusted correctly. You won’t be getting a lot of support from the straps, but they still need to be tight enough to stay up on your shoulders! (And, of course, not so tight that they painfully dig into your flesh). If you find after sufficiently tightening your straps that they still slip down, it could be a sign that your band is too loose. This is because the band may ride up in the back, causing the straps to move up, become looser, and slip down.
A similar issue can occur with the front of the bra if the breast does not fully fill the entire cup, either because the cup is too big or the cut of the bra is not right for the breast shape, even if the cup size is right for the breast size (more on this later). The loose space in the top of the cup can cause a loose strap that slips down.
Those with narrower shoulders need to make sure their bra straps are not set too wide apart on the bra, or the straps may slip down regardless of how the bra fits. You can also consider wearing racerback bras if you have this issue.
Band Makes Straight Line Across Back
Your band should not ride up in the back, but should make a straight line across it at the same level as the front part of the band. If the band is riding up, that’s a sign that it is too loose and you need to go down a band size.
Gore Lies Flat
In an underwired bra, the gore—the little piece of fabric in between the cups—should lie flat between your breasts and be flush against your sternum. (On non-wired bras, gore won’t lie completely flat, but it should be close to flush). If it’s not, it can be a sign of several things.
- Cups are too small—if cups are too small, there may not be enough “room” for the gore to get down between your breasts. Try going up a cup size.
- Band size is too large—if band is too loose, gore may be riding up or simply too loose to conform to your body.
- Bra is the wrong shape for your body—a lot of gore fit has to do with how close-set your breasts are. Close-set breasts will need a low, short gore, like those found in plunge bras. Average-set breasts will do best with a higher gore to provide more support in the middle of the breast tissue. Wide-set breasts will do best with a low-to-medium height, wider gore.
Note that if your sternum is curved inward, your gore may not lie completely flat against your body no matter what you do. My sternum is curved inward like a bowl and most gores will only lay flush with my chest at the bottom. This is a condition called pectus excavatum and unless the case is particularly severe, it is generally asymptomatic.
No Breast Tissue Overflow
In a properly fitting bra, there won’t be any overflow of breast tissue either over the top or the sides of the cup. If the underwire is digging into the outside of your breast, and there’s breast tissue exposed along the side of the bra, the cup size is too small. The cups could also be too close-set for your bust. If the top of the cup is digging into your breast tissue and creating quad-boob, the culprit’s a too-small cup again. The underwire should completely encase the base of your breast, and the cup should be filled but not overflowing.
Cups Don’t Gap
On the flip side, cups shouldn’t have empty space or gap at the top, either. If there are any gaps where the cup isn’t filled with breast tissue, there are three incorrect fit possibilities:
- The cups may be too big. Try sizing down a cup size.
- The cups may not be the correct distance apart for your breasts. Cups that are too wide- or close-set for your body won’t properly encase breast tissue and may be empty at the top.
- The bra could simply be the wrong cut for your breast shape, even if the cup measurement is right for your breast size. For example, if the cup fits well at the bottom but there’s still some space at the top, you probably have shallow breasts and you may need to try a different bra cut. A demi bra with less cup coverage or a balconette may work better for you. There’s more on breast shape in the bra fit troubleshooting section.
How to Measure Bra Size: Complete Bra Size Guide
It’s critical that we state a couple of things here: first, bra fitting is an art, not a science. The process of taking bra measurements is going to involve first getting a starting point. Once you find that starting point, you’ll need to actually try on bras to get some further size precision.
Also, even once you know your size, you may not always be the same size in every brand and cut of bra! More on that later. For now, here’s the four-step process for how to measure your bra size.
Step 1: Put On a Bra…Or Not
There are two ways how to measure bra size: with a bra on or with a bra off. If you have a non-padded bra that you think fits more or less okay in the cups, you can measure with that bra on. If you think you may be in a completely wrong size and none of your bras really fit, don’t wear a bra. You can also try both methods and see what works best for you.
Step 2: Measure Your Band Size
Next, we’ll measure the band size. This will involve taking your underbust measurement. Bust out a soft measuring tape for this (pun not intended). Barring that, a string that you can measure against a yardstick or retractable measuring tape will work fine.
The key to getting an accurate underbust measurement is to position the tape measure (or string) right at the base of your breasts, where they meet your ribs. Then you’ll want to exhale (so you get the smallest measurement) and measure all the way around your torso, keeping the tape straight all the way around. It can be helpful to look in the mirror to make sure the tape isn’t riding up or down across your back. You should keep the tape snug, but not so snug that it digs into your flesh.
Once you’ve got the measurement, note it down. Now you’ll figure out your band size.
Band sizing goes by even-inch measurements. What do I mean by this? The smallest standard band measurement is 28 inches (although specialty brands go down all the way to 24), then 30, then 32, then 34, and so on.
To get your most accurate band size, you’ll first want to round your underbust measurement to the nearest inch. So if you are 30.9”, that’s a 31. If you’re 43.4”, that’s a 44. If your nearest inch is an even number, that’s your initial band measurement. If your nearest inch is an odd number, add one inch and that’s your initial band measurement. (So, if your nearest inch is 31”, you’ll start with a 32 band.)
Some guides will tell you to add four inches to your initial rib measurement to get your band size. This is because when lingerie (and bra sizing) were first standardized, materials were much less elastic, so the extra four inches were necessary for things like breathing (important!). However, now that bras are made of material that is both elastic and supportive, adding four inches is typically not necessary. This is especially true for ladies with higher band sizes; adding four inches will usually give you a bra with a too-loose band and too-small cups. And most of the support comes from the band, so it’s important that it’s tight enough to hold up your bosom!
With that said: if your initial band measurement is on the smaller side (in, say, the the 26-34 range), you may need to go up 1-2 band sizes for comfort. Otherwise, your band may be digging directly into your ribcage when you breathe—uncomfortable! For example, my rib cage measures in at 29”, which would put me in a 30 band. However, 30 bands are uncomfortably tight for me, so I wear a 32 instead.
So if you try on something in your initial band size and its too tight, size up! Just make sure to also adjust your cup size down accordingly if you do so (see step four for clarification on this point).
Nordstrom offers this helpful chart for what underbust measurements typically fit into what band sizes. But remember, this isn’t exact! It’s entirely possible that your 30-inch ribcage will be most comfortable in a 30-inch band. But it could also be most comfortable in a 34-inch band! That’s why you have to actually try on bras to be sure.
The key takeaway for this step is that you need to write down your initial band size—your rounded underbust measurement if even, your rounded underbust measure +1 if odd—with the caveat that this is only a preliminary measurement and you may need to adjust later, when you actually try on bras.
Step 3: Find Cup Size
Next, you’ll need to find your cup size. Contrary to popular belief, cup size is not an absolute measurement. That is, a 32D is a different size than a 36D is a different size than a 40D.
Cup size actually expresses the proportional relationship between the band measurement and the breast volume/breast size. Thus, cup size is basically meaningless without a band size.
Finding your cup size is a two-step process: first, you’ll find the bust measurement. Then, you’ll determine the cup size.
Step 3A: Measure Bust
To find your cup size, you need to get an accurate measurement across the most voluminous part of your breasts. If you’re wearing a bra, you can take the measurement standing up, positioning the measuring tape (or string) across your breasts at about nipple level. You may want to use a mirror to make sure that the tape stays straight around the back. You want to pull tight enough to get an accurate measurement, but not so tight that you start to compress breast tissue.
Note that the tape shouldn’t go down into your cleavage, but should go straight across your breasts.
If you aren’t wearing a bra, you’ll want to bend over parallel to the floor to ensure that you get all of your breast tissue in your bust measurement. This is because there is often breast tissue along the side of the body. With the help of gravity, the breast tissue along the side of the body will get included in your bust measurement when you bend over at the waist. Again, measure at about nipple level, and pull the tape tight enough to get an accurate measurement but not so tight as to compress breast tissue. And make sure the measuring tape is straight in the back and doesn’t ride up or down!
Once you have the bust measurement, note down this number.
Step 3B: Determine Cup Size
Now it’s time to figure out your cup size. You’ll want to subtract your initial band measurement from your bust measurement. Round this number to the nearest inch. (Important note: We are subtracting the band measurement, not your underbust measurement. So if your underbust measurement was 31 inches, your band measurement is 32 and that’s what you’ll subtract from your bust measurement.)
For example, if your bust measurement was 33.7 inches and your initial band measurement was 30 inches, 33.7-30 = 3.7. Rounded to the nearest inch, that’s 4.
This number expresses the size difference between your bust and your band, and reveals your cup size.
See the chart here for how the difference in your band and bust relate to cup size:
Band and Bust Difference Cup Size Chart
| Number | Cup Size |
| .5 | AA |
| 1 | A |
| 2 | B |
| 3 | C |
| 4 | D |
| 5 | DD/E |
| 6 | DDD/F |
| 7 | G |
| 8 | H |
| 9 | I |
| 10 | J |
| 11 | K |
| 12 | L |
| 13 | M |
| 14 | N |
| 15 | O |
Step 4: Experiment!
Now that you know how to measure bra size, you’ll have a first start to try out. Your initial size is going to be your initial band size and your cup size. So if my initial band size is 32 and my initial cup size is C, my initial size based on my bra measurements is 32C.
The next step, then, is to go to the store and try on some 32C bras!
If you try on a few from different brands and styles and they aren’t working, try the following adjustments.
If the band is too tight:
If the band is too tight, go up a band size. If the cups are fine and it’s just the band that’s the issue, you’ll also need to adjust your cup size to keep the cups themselves the same volume in the new band.
For every band size you go up, move down a cup size (so, if you are switching from 32B to a 34, that would be a 34A).
If the band is riding up:
If the band is riding up, it’s probably too loose. Go down a band size. If the cups are fine and it’s just the band that’s too loose, you’ll need to adjust your cup size in the new band to keep the volume the same. For every band size you go down, move up a cup size. So if you are moving from a 32B to a 30, your new cup size would be 30C.
If breast tissue is spilling out of the cups:
If breast tissue is spilling out of the cups on the sides or up over the top of the cups, your cups are too small. Same thing if underwire is digging into the side of your boob. Try moving up a cup size while keeping band size the same. If that doesn’t seem to help, the bra cut could be the issue (see the next section).
If cups are puckering:
If cups are gapping away from the breast at the top, cups are too large. Cups should be flush with the surface of the breast. Try moving down a cup size. If that doesn’t work, it may simply be a bra cut that doesn’t work well for you.
Bra Troubleshooting and Other Fit Issues
Even though you know how to measure bra size now, some issues might come up. Here are some other potential issues you may run into with bra fit:
Bra Cut and Breast Shape
32C breasts may all have a fairly similar size, but that doesn’t mean they are the same. Breasts come in lots of different shapes, and breast shape affects what bra cuts work the best for you.
There are all kinds of breast typing schemas, many from lingerie companies. However, they all pretty much rely on various combinations of two metrics: how wide-set your breasts are, and where most of the breast mass is. You’ll want to consider both of these things when you choose bras.
How Wide-Set Are Your Breasts?
We’ve already discussed the need for the gore to lie flush against the sternum and for underwires to completely encase the base of the breast. For these things to be possible, a bra has to be compatible with how far apart your breasts are.
- Close-set breasts: If your breasts are touching or very close to touching, they are close-set. This frequently goes along with a large cup size. It can be hard to find a bra that doesn’t smush your breasts together and provides enough support. If you can find a full-support bra (with a higher gore) that works for you, great. Otherwise, you may want to go with a plunge bra or balconette, since the wires are lower and cups are frequently close-set.
- Medium-set breasts: If you have a little bit of space between your breasts (about a finger’s width), they are medium-set. In this case, many styles could potentially work for you (although anything that compresses to the center too much could give you a bit of a uni-boob). So, you’ll need to more closely consider where most of your breast mass is located.
- Wide-set breasts: If you can fit 2+ fingers in between your breasts, they are wide-set. Your primary concern will be finding bras where the cups are set far enough apart. Plunge, balconette, or t-shirt bra cuts can all work well for wide-set breasts, provided the gore is a little on the wide side. So no plunge bras where the 2 cup underwires are basically touching in the center! Bras with a front clasp also frequently have wider-set cups, which may work well for you.
Where Most of the Breast Mass Is:
Two pairs of breasts can have the same overall volume, but the breast mass can be distributed very differently. That affects what bra is the best choice. Essentially, what area does most of your breast size come from?
- Shallow breasts: In the shallow breast, most of the mass and fullness is at the bottom of the breast. There is typically a shallow slope down to the nipple, and then most of the tissue is concentrated in the lower half of the breast. Cup gapping is an issue with this breast type. Avoid full coverage bras. A demi or balconette style will hold up the fullness at the bottom without leaving empty space in the cup at the top. A padded plunge without too much cup coverage could also work.
- Conical breasts: The conical breast is a little fuller on top than the shallow breast, but somewhat cone shaped overall. Conical breasts are perky and usually on the smaller side proportionally—a C cup or less. Like the shallow breast, you may be prone to gapping, although a wider variety of cup options may work for you. A padded plunge bra in particular will create some fullness up top and keep you supported all around, but experiment with anything that’s not a full coverage or high-support cut!
- Pendulous breasts: These breasts have become somewhat tubular with time and hang down longer than they are wide. You need something to support and shape the tissue. Your best bet is a full-support or full-coverage bra. Because you need something with a deep cup, avoid demi and balconette cuts.
- Round breasts: Round breasts are full all around the breast. This can be natural or surgically obtained. The round breast will fill out a full-coverage bra nicely; many other styles will work, too, although a balconette or demi cut may be too shallow and cause quad-boob. Also, avoid anything with padding or push-up as it will create somewhat unnatural-looking, high-set cleavage.
- Teardrop breasts: The teardrop breast is just slightly fuller on the bottom than the top and is fairly rounded and perky. These breasts will work in pretty much any cup, so consider what will work best with how wide-set your breasts are.
- Uneven breasts: Most breasts are somewhat uneven. But if you have about a cup size (or a little more) difference, you may want to try a push-up with removable inserts. Remove on the larger side, leave in on the smaller side!
Sister Sizes
Maybe you’re normally a 34D, but a particular bra you are trying on has an unusually inelastic band. The 34D is terribly uncomfortable and digs into your ribs. What should you do? (This bra is really cute and you just can’t let it go.)
Well, my friend, let me introduce you to sister sizes. A sister size is a bra/band size combo where the volume of the cup is the same as your regular size, but the band size is different. This allows you to sometimes wear a different band size if necessary—like for a super-tightly banded bra! We’ve already alluded to this concept in step four of our complete bra-sizing process.
Sister sizing works like this: for every band size you go down, move up a cup size. That’s a sister size. For every band size you move up, move down a cup size. That’s also a sister size. So for a 40E/DD, sister sizes would be 38F/DDD and a 42D. You can theoretically move up or down more than one band size this way, keeping cup volume consistent, but I don’t recommend this.
This chart shows what sizes are sisters. Cells that are the same color indicate sister sizes. Again, I don’t recommend moving up or down more than 1 band size, but these sizes do all have equivalent cup volume. I haven’t included all conceivable cup/band sizes for the sake of space, so my apologies if your size isn’t represented in the below chart.
Brand Inconsistency
As maddening as it is, not all brands are totally standard when it comes to sizing. Of course, as cup size is meant to express a standardized difference between breast size/volume and underbust measurement, this shouldn’t be the case, but alas, it is. You may find that while you are normally, say, a 40B, in a particular brand you fit better into a 40C or a 42B and so on. Remember: your size is a starting place. The goal is to get bras that fit properly (remember section two!) without being overly fixated on the number in the bra.
Bra Sizing in Different Countries
Not all countries have identical cup sizing schemas, especially when you get past the D range. So if you’re trying to buy a bra with UK sizing, you might need a different size than your usual American size.
Here’s a conversion chart to help you figure out your bra size according to different sizing schema. Note: UK and US sizes have the same band sizes. European, Australian, French, and Italian band sizes are different.
| American Cup Size | UK Cup Size | European Cup Size |
| AA | AA | AA |
| A | A | A |
| B | B | B |
| C | C | C |
| D | D | D |
| DD/E | DD | E |
| DDD/F | E | F |
| G | F | G |
| H | FF | H |
| I | G | J |
| J | GG | K |
| K | H | L |
| L | HH | M |
| M | J | N |
| N | JJ | O |
| O | K | P |
Bra Fit: Key Takeaways
Many women are wearing the wrong bra sizes, with too-small cups and a too-large band the most common fit error. But now you know how to measure bra size!
Here’s how a bra should fit:
- Most support should come from the band
- That said, the properly adjusted straps shouldn’t slip down.
- The back of the bra should make a straight line across your back and shouldn’t ride up.
- The gore (the fabric in between the cups) should lie flat against your sternum (unless your sternum is concave).
- There should be no spillover of breast tissue over the tops or sides of the cups.
- Your breast tissue should completely fill the cups; there shouldn’t be any gapping at the top of the cup.
Here’s how to measure for a bra:
- With a flexible measuring tape, measure around your torso at the base of your breasts to get your underbust measurement. Round this number to the nearest inch. If this is an even number, that will be your starting band size measurement. If this is an odd number, add one inch, and that will be your starting place band size measurement.
- Next, you’ll figure out your cup size. You’ll do this by measuring around your torso at the fullest part of your breasts. You’ll subtract your starting band size from the bust measurement. Then, you’ll round to the nearest inch. So if my bust measurement was 39.2 and my initial band size was 36, that’s 39.2-36 = 3.2. Then, I’ll round that to the nearest inch, which would be 3. Each inch corresponds to one cup size letter. So 1 inch = A cup, 2 inches = B cup, 3 inches = C cup, and so on.
- Once you have a starting measurement, you’ll need to try on bras to finalize your size.
If you try on several different brands, cuts, and styles in your starting size and none of them are working, here’s how to adjust:
- If the band is too tight (but the cups are fine), go up a band size and down a cup size.
- If the band is riding up (but the cups are fine), go down a band size and up a cup size.
- If the band is fine but breast tissue is spilling out of the cups on the top or sides, or the cups or underwire are digging into any breast tissue, go up a cup size in the same band.
- If the band is fine but there’s gapping in the cups, either try a different bra cut or move down a cup size in the same band.
Once you’ve found the correct size, you may still run into some bra issues. Here are some points of bra fit troubleshooting:
- Bra cut and breast shape: not all breasts are shaped the same. So even if you are in the correct size for your breast size, not all bra types in that size will necessarily fit you correctly.
- Sister sizing: Sister sizing describes bras where two bras have different band and cup sizes, but the cups are the same volume. For example, a 30D has the same cup volume as a 32C has the same cup volume as a 34B. You may want to take advantage of this information when dealing with an unusually tight or loose band.
- Brand inconsistency: Not all brands size their bras exactly the same. There may be some brands where you will consistently need to size up or down a cup size.
- Bra size conversions between countries: if you’re trying to buy a bra in a country other than America, make sure you know how their sizing system corresponds to ours!
Ride on, bra superhero—you’re ready to take on the lingerie department!
