Stop Guessing Your Bra Size
If you have a drawer full of bras that you tolerate rather than love, it’s likely that you’re wearing the wrong bra size. When it comes to bra sizing, one size does not fit all and finding the right size bra is essential for everyday comfort, support and confidence.
Our step by step instructions to measure your bra size at home will have you reaching for your new favorite bra in minutes.
Our bodies change constantly, and with daily wear, it's only natural that your bras will change over time too. We'd recommend re-measuring every six months, to make sure that you're still getting the support you need.
How To Measure Your Bra Size At Home
Step One: Measure Your Band
Most people measure too loosely here because a snug tape feels uncomfortable, so trust the process with this step. We’d recommend measuring in inches, this will make calculating your bra size later on easier.
Wrap the tape firmly underneath your bust, where the band naturally sits. You’re looking for a snug fit with just enough room for two fingers underneath. If you land on an odd number, round up to the nearest even inch. That’s your band size.
Step Two: Measure Your Bust
Measure the fullest part of your bust, bringing the tape from your back around to the front across your nipples. Make sure to keep it level and flat rather than pulled tight. Note the number down because you’ll need it for the next step.
Top tip: Measure over bare skin or a thin top where possible. Measuring over a padded bra will throw your reading off.
Step Three: Calculate Your Cup Size
Don't worry, there's no complicated math involved here, we promise.
Cup Size = Bust Size − Band Size
The difference in inches maps directly to a cup size. As a quick example: if your bust measures 34 inches and your band size is 30, the difference is 4, which puts you at a D cup.
Use the bra size calculator below:
Fit guide
Find your bra size
Two measurements is all it takes. Grab a soft tape measure and wear a non-padded bra for the most accurate result.
Pop both measurements in to get your size.
Your estimated size
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Sizing varies by style — check individual product size guides tooTips For Finding the Right Fitting Bra
There are a few things worth checking before you declare a bra a bad fit.
- A bra band should feel snug, not too tight, not too loose. It should sit level across your back and stay put when you raise your arms. If it rides up, the band is too big.
- Straps should sit quietly on your shoulders. You shouldn’t feel them digging in, or falling down. If you’re constantly adjusting them, the band is doing less work than it should.
- Cups should fully contain your bust without gaps at the top and spillage at the sides. Gaps mean that the cup is too large, while spillage (or “double boob”), means it’s too small.
- Remember, measure over bare skin or a thin top where possible, rather than over an existing bra, for the most accurate result.
- If your measurements are correct but the fit still feels off, it may be the style rather than the size. That's where sister sizing comes in.
What Is Sister Sizing?
Sister sizing is the most useful concept in bra fitting. Bra sizing is not standardized across brands, which is why a 32C from Lounge may fit differently to the same size from another brand, or across different styles. The measurements, cut, and stretch in materials all vary. Which means your correct size and your perfect fit are not always identical.
Sister sizes let you adjust for that, by moving both the band and cup together to find a better fit. Moving up a band size and down a cup size keeps the overall volume in the cup roughly the same, while offering you more room across your back and changing how it sits on your body. Moving down a band and up a cup does the opposite.
For example, a 32D, 34C and 30E are all sister sizes. If your usual size feels tight around the band or loose in the cup, try sizing up on the band and down on the cup. If it's the opposite, size down on the band and up on the cup. Read our full guide to sister sizing here.
Finding the Right Size Bra at Lounge
One thing to note is that wireless bras and bralettes have different sizes and are measured from XS to XXL rather than on band and cup size, but you can find our size guide to find your size here.
From wired to non-wired bras, find a bra that fits you - not the other way around. We offer hassle-free exchanges, so if you're not completely sure about your size, feel free to swap it for one that suits you better. Bra sizes can sometimes feel different depending on the bra style and brand, so finding the perfect bra for you can sometimes mean trying a couple of different sizes.
Bra Fitting FAQs
Do Different Bra Styles Fit Differently?
Yes. The same size can feel different depending on the style. Push-up bras tend to fit slightly more snug in the cup, since the padding adds volume. Plunge bras sit lower and can feel different across the bust than a full-cup style. Non-wired and bralette styles run on their own XS - XXL sizing rather than band and cup, so they won't always match your wired size directly. If you've found your true size but a specific style still doesn't feel right, it's usually the style, not your measurements.
How Often Should You Measure Your Bra Size?
We'd recommend checking your size every six months. Weight changes, hormonal shifts, pregnancy, and even general wear on a bra's elastic can all affect fit, so a size that was right six months ago might not be right now. If you've had any of the above happen, or your usual bra suddenly feels different, it's worth re-measuring sooner rather than waiting it out.
What If My Measurements Fall Between Two Sizes?
It happens more often than you'd think, and it usually comes down to personal preference rather than a wrong measurement. If you're between two band sizes, go with the smaller band paired with a sister size in the cup, since bands stretch slightly with wear and a too-loose band won't give you the support you need. If you're between two cup sizes, it depends on what you're after: a smaller cup gives a closer, more contained fit, while sizing up gives a little more room to move.
Can Wearing the Wrong Bra Size Affect My Health?
More than most people realize. An ill-fitting bra worn consistently over time can contribute to back, neck and shoulder pain, poor posture, skin irritation and headaches. Less obvious symptoms include restricted blood circulation, numbness in the fingers and even digestive issues like indigestion, which can occur when a band that's too tight puts pressure on the chest wall. Getting your size right isn't just about comfort, it's a form of self-care that your body will genuinely notice.
