How to Accurately, Correctly and Easily Measure Your Bra Size with Photos
— NSFW Warning —
This article includes educational photos that display bare or minimally covered breasts to demonstrate accurate bra measuring technique. If you prefer to avoid this content or if you're in a public or shared space, please proceed with caution or skip past the photos. Be respectful of the model in any messages or comments.
Note: The article is in Beta, so if you have any feedback on the article with how to clarify or improve it—we'd really appreciate hearing from you! You can reach us HERE.
How to Accurately Measure Your Bra Size at Home: Two Proven Methods
Finding your true bra size can be life-changing. Most people wear the wrong size—often too big in the band and too small in the cups—leading to discomfort, spillage, or gaping. The good news? You can measure accurately from home with minimal tools.
Our Billy's Bras At-Home Bra Size Measuring Kit makes it easy and modest: it includes a 120" (300cm) soft tape measure (perfect length for wrapping around comfortably with plenty of extra) and reusable silicone nipple covers for privacy if you're measuring braless.
In this guide, we'll walk you through the two most reliable methods:
- The classic Band + Bust method (quick and widely used).
- The more precise ABTF 6-Measurement method (from the A Bra That Fits community, ideal for better accounting of breast shape and projection).
Tips before starting:
- Measure braless for accuracy (or in a very thin, fairly loose t-shirt if absolutely necessary). Not adding any bulk or support is key for accurate measurements.
- Use the silicone nipple covers from your kit for modesty. They are thin enough to not affect your measurements.
- Stand naturally with relaxed posture—don't suck in or puff out and keep your shoulders squared and straight.
- Breathe normally; exhale normally for each of the measurements.
- Take measurements in inches (most US brands use inches). Use centimeters if you need or prefer international sizing.
- Measure to the nearest ¼ inch for best results.
- Measure in good lighting (ideally with a mirror) alone or with helper to keep the tape level. Being able to read the measurement can be a struggle in too-dim lighting.
What about Your Current Bra Size?
You're likely already in a bra size that you've been more or less using. After all these measurements, we hope you confirm that it's been correct all along! But, don't assume it is before starting and definitely don't be shocked (or dismiss) if you find the size you've worn is dramatically different to the calculated size.
There is a high probability that the size you've worn is too big in the band and too small in the cup. Think you're a 36C? Don't be surprised to learn you're actually a 32G. You've been warned! (Trust us, it's a good thing.)
Which Method Should You Use?
Start with Band + Bust for speed. Great for quick, periodic re-checks.
Switch to ABTF for a more accurate measurement, especially if bras gap, pinch, ride up, or feel off for shape. The best for a fresh start or deep dive measure.
Method 1: Band + Bust ("Traditional" Method)
This is the classic approach many stores, brands and generations of women have used. It gives a solid starting point, though it can underestimate cup size for some shapes.
— NSFW images below here —
Step-by-Step Guide
1a. Measure your underbust (band size)
Wrap the soft tape measure from your kit snugly, but not painfully tight, around your ribcage, directly under your breasts where a bra band/underwire sits. This may be up and behind breast tissue as shown below. Keep it level all the way around your body and parallel to the floor. Exhale gently and read the measurement. We recommend writing it down to reference later.
Common mistakes:
Pulling too tight (or sucking in) → band too small
Leaving it too loose → band too big and will lack support
Not measuring directly under your breasts → inaccurate measurement
Not keeping band level → inaccurate measurement (too big usually)
1b. Find your band size
If it's an even number (e.g., 32), that's often your band. Don't add anything to it. This is your band size!
If it's an odd number (e.g., 33), round to nearest even (usually up to 34). Don't add anything to it. This is your band size!
Quick note: Some brands add 4–5 inches to a very snug measurement for "comfort," but we are avoiding that here since you want a true measurement that isn't tied to your cup size. Remember: your band measurement IS your band size. It's that simple.
2a. Measure your bust
Wrap the tape loosely around the fullest part of your breasts (usually at nipple level), keeping arms as relaxed as possible if you're holding your own tape. Don't squeeze the tape tightly around yourself—have the tape just snug enough so it stays up and level. Zero compression is the goal. Write this measurement down for reference.
2b. Find your cup size (US sizing)
Subtract band measurement from bust measurement. The result is your cup size:
0–1 inch = AA or A
1 inch = A
2 inches = B
3 inches = C
4 inches = D
5 inches = DD/E
6 inches = DDD/F
And so on (each inch = one cup letter).
Example:
Model's underbust measurement is 32", which is her band size.
To find the cup size, use the underbust minus bust formula.
Model's underbust measurement is 32" and her bust is 37"
Using the formula: 37" minus 32" = 5"
5" of difference is a DD cup.
So, her bra size per her measurements is a 32DD. (More on this below)
Common mistakes to avoid in this method:
Measuring bust too tightly or not across fullest part → cup too small.
Tape isn't kept level. See below for what an unlevel tape looks like. This happens so easily! Having a mirror or a helper really does help. You're trying to do so many things at once, and keeping your posture correct, the tape level on two sides plus the front plus the back, and reading the measurement all at once is a lot!
Be patient as you measure and don't stress or rush. Just adjust and triple-check that everything is positioned right and level everywhere before reading the tape. Patience—you will get it eventually.
Keep going to make sure you don't measure unlevel as shown below.
Adding too many inches to band (old +4/+5 rule) → loose band, requires incorrect smaller cups.
Not exhaling → underbust and band size too large.
Wearing a bra for measurements → inflates both band and bust measurements.
Ignoring sister sizes when finding perfect fit (e.g., 30FF ≈ 32F volume).
Quick note: This method works well for shallow to average projection but may suggest too-small cups if breasts are fuller/projected. This is definitely true for the model shown as you'll see.
Method 2: ABTF 6-Measurement Method (More Accurate & Shape-Aware)
Popularized by the A Bra That Fits community, this method uses six measurements to better capture breast shape, projection, and tissue distribution. It's especially helpful if the traditional method feels "off."
Use your kit's soft tape measure. Take all measurements braless (with nipple covers for comfort/privacy). Keep tape level, body relaxed. A helper and/or mirror is just as helpful with this method as the first one above. We recommend writing each measurement down, along with notes for questions or suspicions about each measurement.
1. The 6 Measurements
#1 — Loose Underbust
Gently loose, like a very light hug. The tape is on your skin but not being pressed/pulled into it. Measure just under your breasts where the tissue meets your ribcage. You might be up and behind your breasts as shown below.
#2 — Snug Underbust
Think "firm hug" and exhale. It's basically a comfy but supportive bra band. It's tight and wouldn't move or shift, but it isn't trying to suffocate you. See below for "snug" example.
#3 — Tight/Super Snug Underbust
As tight as possible without pain. You're aiming for where your skin and tissue no longer compress. Don't hurt yourself, but go tight on this measurement to get through any "fluff." Below is a good example of how tight you should go.
#4 — Standing Bust
Arms at sides, loosely over fullest part. This is basically the same measurement and technique as the Band & Bust method above. It needs to be loosely across the fullest part of your breasts, which may or may not be across your nipples.
Quick note: You may have a sharp eye and notice the tape isn't exactly across the model's fullest part of her bust, but just below it (especially on her right breast). We left this as is to demonstrate what that may look like. Your task is to do better than shown!
#5 — Leaning Bust
This one can be tricky to keep the tape in the right spot, especially across your back. Use a mirror or helper. Bend forward 90° or as close to that as you can, and measure loosely over fullest part. Try your best not to have the tape supporting your breasts at all—let them hang down as far as they will, and measure that.
Quick note: Measuring this fully topless matters a lot so that your projection is fully accounted for. Any support, however minimal, will skew this number too small.
#6 — Lying Bust
Same as above, this can be tricky to measure correctly. Just be patient and get the tape in the right spot. If your boobs are big and tend to flop all over the place when you lay down, aim for getting them directly off to your side instead of up higher or down lower on your chest. Lie flat on your back and measure loosely across your back, sides and breasts. Zero compression with the tape here!
Quick note: Measuring this fully topless matters for the same reason as the Leaning measurement. Having any support here is not your friend.
2. How to Calculate Your Size
Let the calculator do it
Input the six measurements above into the ABraThatFits calculator and let it do the math.
If your numbers are all over the place the calculator may reject them or give you an incorrect answer. If you have a wild range or two numbers don't seem right to you—re-measure those.
Generally you can assume that:
The first three measurements should go smaller (i.e. 37", 36", 34"), not jump around or be super similar. The exact range depends on your build.
The leaning and laying bust measurements are usually bigger than the standing bust measurement. The bigger they are, the more "projected" your breast shape is.
For the model, the measurements were:
Loose underbust: 33"
Snug underbust: 32"
Tight underbust: 30.5"
Standing bust: 36"
Leaning bust: 40"
Laying bust: 39.5"
The calculator provided size 32DDD and sister 34DD
The cup size is one larger than calculated by the first two-step method because her breasts are projected and soft tissue, meaning the bust measurement didn't fully account for all of her breast tissue (it was hiding close to her body). The 6-measurement ABTF method "saw" it better because of the Leaning and Laying measurements, though. Neat!
Common mistakes in ABTF method:
Skipping leaning/lying → underestimates projected shapes. Don't skip these.
Tape not level → wrong, unexpected and/or confusing measurements.
Rounding band up too much or not being precise → With ABTF calculator, round to nearest 1/4" or 1/2"; anymore than that will produce weird calculations for you (too small or too big)
Wearing a bra for measurements → distorts both band and bust. Go topless and ditch the bra so that you're measuring your body and not a bunch of fabric.
Ignoring sister sizes when finding perfect fit (e.g., 30FF ≈ 32F volume).
Related, remember cup sizes mean nothing by themselves. A "B cup" isn't small and a "DD" cup isn't big. The volume of your breasts' tissue is expressed in the relationship between band and cup size. Confused? Read more about breast volume and cup sizes RIGHT HERE.
Final Tips for Success: How to Fit a Bra
OK, so you have a bra size measured/calculated! Great! So you're all done and ready to jump online to order that size, right? Well, probably not, no. Sorry.
You can be super confident that measuring them as you did above puts you really close to the right size. It's just fine tuning from here! The bra size you just calculated is your best starting point.
You should double check it by trying on some bras from your favorite (and a few others) brand in your preferred style in your calculated size. Then...evaluate. See where it's great, where it isn't, and how it feels. Adjust from there to zero in on the right bra in the right size for your body and goals.
In the meantime, you can read more about the specific topics and issues related to bra fitting:
Read this post about general bra measuring and fitting tips
Read this post about common measuring mistakes and how to fix them
Read this post about breast shapes and how they affect a good bra fit
Second, always "scoop and swoop" when trying bras. Look at the model's left breast (right side of the photos). Super important!
The first photo is before any "Scooping and Swooping." Her breast is in the cup, but there's a lot of tissue being left out and not properly supported (and being cut across by the outside of the underwire).
The center photo shows her reaching deep into her bra cup and scooping the tissue up from her side and down in the cup and bringing it into the cup and more centered. This forces all of the breast tissue to actually be cup instead of outside, especially on the sides.
The last photo shows the difference after scooping and swooping, which also happens to show that her cup size is much too small.
Third, bands should be snug on loosest hook row. See below for which hook that is. It's sometimes called the "outside" or "outer" hook. You can call it whatever you want, but it's the hook that makes the band as big as it can be. The other, tighter rows are there to account for band stretch as the bra's elastic wears and relaxes. So start big so you have room to adjust later.
Cups should always enclose and support breasts. Simply put, 100% of your breasts' tissue should be fully within the bra's cups. Not spilling over the top or center. Not off to the sides where the underwire is actually on it. Not falling out the bottom. Not poking out of the top or sides with the cup on your breasts instead of around them.
Quick note: Bras that have less-than-full coverage, such as balconette, demi, and plunge styles won't fully cover your breasts. But, that doesn't mean your breasts shouldn't be enclosed and fully supported without poofing out anywhere they aren't covered.
Good fit is dependent on several factors: proper bra sizing (including both band and cup size), breast root width and height, and whether your breasts are shallow or projected (read here for more on that topic). We can help get you a great bra fit—just ask us!
Continuing from above, there shouldn't be any gaps in cups as shown below. Counterintuitively, this is usually caused by too small a cup size rather than too big. This is ultra common with +4 sizing (read about that here) that results in a too-big band paired with a too-small cup. Remember, your breasts should fill your bra's cups, and your bra's cups should encapsulate your breasts.
Lastly, re-measure every 6–12 months or after life changes. If you feel your body has changed—re-measure! Or at least take some quick test measurements to see if they've changed. Your kit makes this discreet and easy so you stay on top of your body's changes.
Hot tip: Keep a small journal or log of your measurements with dates, weights, good vs bad bra fits, etc.
Get More Help
Measuring at home is genuinely empowering, but sometimes the numbers feel confusing, or you're not 100% sure about your technique. That's completely normal—bra measuring/sizing/fitting isn't always linear or crystal clear. Shape, tissue distribution, and even slight posture differences can make a big impact. And yes, your body changes on you without warning! Ugh.
If any of these sound like you, we're here to help:
Your calculated size feels "off" compared to what you've worn before (or bras in that size don't fit right when you try them). Or your measurements don't seem to make sense together.
You're getting very mixed results between the Band + Bust and ABTF methods. It's common to have different results by one band or cup size, but more than that means some other questions need answers.
You're unsure if your tape was level, snug enough, or if you're measuring correctly (fullest part, 6 measurements, tape snug vs too tight, etc).
You have questions about sister sizes, projected vs. shallow shapes, full-on-bottom/full-on-top, or anything else bra-related. In other words, you've measured but don't know where to go from there. Maybe you feel more lost than ever.
Send us your measurements (and optional photos) for a personalized second opinion - Many people find it helpful to share:
Their 6 ABTF measurements (and/or Band + Bust numbers)
Photos of the tape in place during all or specific steps (underbust, standing bust, leaning bust, etc.)
Photos of your breasts for an evaluation of shape, including root width and height, shallow versus projected, tissue migration, fullness distribution, and other aspects that influence choice of bra brands and styles for the best fit.
Comparison photos of bra fit in old size vs new, different styles or brands in various sizes, or other clusters or variables that they'd like a second opinion/evaluation on.
Hot tip: The reusable silicone nipple covers included in your Billy's Bras At-Home Measuring Kit are perfect for this—they provide full modesty and coverage so you can snap photos comfortably and privately without feeling overly exposed. Simply apply them before measuring or photographing (they're adhesive, reusable, and easy to remove/wash).
We're happy to review and suggest refinements, confirm your size, clarify measurement steps, and recommend next steps (like trying a sister size or specific styles).
How to get in touch:
Use the contact form on our website for general questions.
For photos or detailed measurement reviews, you can also email us directly at billysbras@gmail.com where treat all submissions confidentially and delete after helping.
No question is too small or a bother—whether it's "Is my cup size really that big?" or "Help, I got a 28 band—what now?"—we've got you. Drop us a line and let's get you in the perfect fit.
Shop our available bras:
Use the Search to find all the bras in a particular size, or Filter results within a specific brand or style search result.
You can view all of our bras here: All Bras
You can also request your size, brand or specific style here: Billy's Brassierge
Now go measure your way to the best-fitting, most comfy bra you've ever worn. You've totally got this! And we are here to back you up however you need. It really will change your life (and how you view and think of your body).
We are really proud of you for taking this step forward.