How to Size a Bra: BRABAR Fit Guide and Bra Size Calculator
How to Size a Bra: Quick Summary
To size a bra accurately: (1) measure your rib cage directly under your bust, rounded to the nearest even number, for your band size; (2) measure the fullest part of your bust; (3) subtract band from bust — each inch of difference equals one cup size, starting at A. A 34-inch band with a 38-inch bust (4-inch difference) is a 34D. The full step-by-step walkthrough is below.
BRABAR PHILOSOPHY - THE E-Z FIT METHOD
Your bra should fit like a strapless bra, hugging your ribcage not hanging from your shoulders. A comfortable bra means a confident you. Our EZ-fit method teaches girls to find the correct band measurement: essential to a proper fit. It's super easy to measure yourself at home.
Bra Size Chart
Cross-reference your band size (rib cage measurement) with your bust measurement to find your cup letter. Find your band size down the left column, then follow the row across to where it meets your bust measurement.
| Band Size | A Cup (Bust) | B Cup (Bust) | C Cup (Bust) | D Cup (Bust) | DD/E Cup (Bust) | DDD/F Cup (Bust) |
|---|---|---|---|---|---|---|
| 28 | 29 | 30 | 31 | 32 | 33 | 34 |
| 30 | 31 | 32 | 33 | 34 | 35 | 36 |
| 32 | 33 | 34 | 35 | 36 | 37 | 38 |
| 34 | 35 | 36 | 37 | 38 | 39 | 40 |
| 36 | 37 | 38 | 39 | 40 | 41 | 42 |
| 38 | 39 | 40 | 41 | 42 | 43 | 44 |
For example, a 34-inch band with a 38-inch bust (4-inch difference) is a 34D. Not sure of your band or bust measurement yet? The full step-by-step method is right below, or see many more worked examples across every band size.
STEP 1
MEASURING BAND SIZE
Your ribcage measurement is your band size measurement.
To measure the ribcage, measure directly underneath the bust, swinging around the ribcage. Round the measurement to the nearest even number shown to determine the band size.
Jot down this number.
The band size is your ribcage measurement rounded to the nearest even whole number.
Round to nearest even number to determine your band size.
Your Rib Cage = 33 inches = 34 Inch Band Size
BAND SIZE CHART
| RIB CAGE MEASUREMENT (in) | BAND SIZE |
|---|---|
| 27, 28, 29, 30 inches | 28-30 AA up to DDD - Small |
| 31, 32, 33, 34 inches | 32-34 AA up to DDD - Medium |
| 35, 36, 37, 38 inches | 36-38 AA up to DDD - Large |
STEP 2
MEASURING BUST SIZE
Next, we'll look at measuring the bust. Your bust size is the width of your chest at your bust's fullest point.
Wrap the soft measuring tape over the fullest part of your bust.
Hold the measuring tape parallel to the floor while measuring around the back, starting at the fullest part of the bust. Then, round to the nearest whole number to get your bust size. The reading on the tape, in inches, is your bust size.
Jot down your bust size measurement.
Your Bust Measurement is 37.8 = 38 inches.
STEP 3
HOW TO FIND YOUR BRA CUP SIZE
BUST – BAND = CUP
Now you can find your bra cup size using the bust measurement you just took.
Subtract your band size from your bust size to get your cup size. The cup capacity is calculated in inches: A cup = 1 inch | B cup = 2 inches | C cup = 3 inches | D cup = 4 inches | DD cup = 5 inches | DDD cup = 6 inches.
Your cup size describes the volume of your breasts relative to your band — the difference between your bust measurement at its fullest point and your band measurement at your rib cage.
Bust size − Band size = Cup size in inches. For example, a band size of 34 inches and a bust size of 38 inches gives a difference of 4 inches, which is a D cup.
Once you've calculated your cup size in inches, match it to the cup letter in the table below.
| Cup size | Cup size in inches |
|---|---|
| A | 1 |
| B | 2 |
| C | 3 |
| D | 4 |
| DD | 5 |
| DDD | 6 |
STEP 4
THE CORRECT BRA FIT: FIND MY BRA SIZE
Combine your band size number and your cup size letter, and that's your bra size.
Bra size = Band Size Number + Cup Size Letter
Use our calculator below to find your bra size instantly.
THE PROPER FIT
Does the size you received after measuring surprise you? Certain factors can cause you to change bra size, including a gain or loss in weight, a new exercise regimen, pregnancy, and a fluctuating diet. The bra band will slightly change the size you require, otherwise known as a "sister size" to compensate as an alternative. Unfortunately, these sizes are often too large in the band area and too small in cup size leading to unnecessary discomfort.
WHEN IT'S TIME TO GET A FITTING: SIGNS OF A BAD-FIT
It's important to find your bra size and measurements every 6 months or every year at the very least. Our bodies are constantly changing and getting your measurements right are crucial to ensure you're wearing the right bra size. Here are some tell-tale signs your bra needs to go!
- Cups show visible wrinkling (a sign your cup size is too large)
- Cups show visible gapping (a sign your band size is too large)
- Your breasts spill out of your cups at the corners (a sign your cup size is too small)
- Your bra band rises up your back (a sign your band is too loose)
- Your bra band pinches your skin (a sign your band is too tight)
- Straps pinch your skin even after adjustments (a sign your band is too loose and your straps are doing all the heavy-lifting)
- Straps fall off even after adjustments (a sign your band size is too large)
- Your bra hikes up whenever you lift your arms (a sign your band is too loose)
Do you find yourself with any of the above bra complications? Book yourself a professional fitting service or read more about how to measure yourself.
What If You're Between Sizes?
Not every body lands exactly inside a listed size, and that's okay. BRABAR's flexible, stretch-knit construction genuinely extends beyond the labeled range in both directions.
Measuring Below a 28 Band
If your rib cage measures around 26 inches, our flexible styles comfortably accommodate that through sister sizing and the fabric's natural stretch. Best options: the HUG collection, the Everyday Bra, the Soft Cami Bra Top, and the Soft Multiway Convertible Bra.
Measuring Fuller Than DDD/F
Certain styles are cut with enough capacity and stretch to comfortably support fuller, H-cup-range shapes, even without an H label on the tag. Best options: the Soft V Lace Bralette, the Strapless, the Multiway, and the Halter styles.
Still not sure? Reach out directly and we'll help you find the right style for your measurements.
Frequently Asked Questions
How do I size a bra?
Measure your rib cage directly under your bust (rounded to the nearest even number) for your band size, then measure the fullest part of your bust. Subtract band from bust — each inch of difference is one cup size, starting at A. A 34-inch band with a 38-inch bust is a 34D.
How do I use a bra size chart?
Find your band measurement (rib cage, in inches) along one axis and your bust measurement along the other. Where they intersect gives your cup letter — for example, a 33-inch rib cage (34 band) and a 38-inch bust (4-inch difference) is a 34D.
What if I measure smaller than a 28 band?
BRABAR's flexible styles, including the HUG collection, the Everyday Bra, the Soft Cami Bra Top, and the Soft Multiway Convertible Bra, use stretch-knit construction that comfortably accommodates a 26-inch band through sister sizing and the fabric's natural give.
What if I measure fuller than a DDD/F cup?
Certain styles, specifically the Soft V Lace Bralette, the Strapless, the Multiway, and the Halter, are cut with enough capacity and stretch to comfortably support fuller, H-cup-range shapes, even though the label tops out at DDD/F.
How accurate is an online bra size calculator?
An online calculator is only as accurate as the measurements you enter. Using the rib cage method (measuring directly under the bust, with no inches added) gives far more accurate results than the older add-4-inches method most calculators default to. See many worked examples for a range of real band and bust combinations.
What if my size is hard to find in stores?
Sizes like 28AA, 28D, 30AA, 32AA, 36AA, and 38A are consistently under-stocked by mainstream brands because they fall outside the most commonly manufactured range. BRABAR carries a full range specifically because these sizes are real and common, just underserved.
Should I measure myself or get a professional fitting?
Self-measuring with the rib cage method is accurate for most people. If you've tried measuring and the result still doesn't feel right, or your body has changed recently, a professional fitting can help confirm the size.
