How to Measure Your Bra Size at Home
To measure your bra size at home, use a soft measuring tape to measure your band and bust size, subtract your band from bust measurement to find your cup size, and then match it to a bra size chart. See below for our full step-by-step guide, bra size calculator tips, and fitting advice.
Finding the perfect bra can be a frustrating and uncomfortable experience. That’s why so many of us stay in the same old bra for much longer than recommended.
But believe it or not, bras are not supposed to feel uncomfortable. The right-size bra can even improve posture, and reduce back pain, all while making your clothing look better.
Below, you'll learn how to measure yourself at home for a new bra, and how to find the best one for your body type with the help of our bra sizing chart.
How to Measure for a Bra: Step-by-Step
Step 1: Gather what you need to measure
The most accurate tool for measuring yourself at home is a soft measuring tape or tailor’s tape. If you don’t have one, you can measure yourself without a soft measuring tape by using a piece of string or ribbon instead (make sure it’s not stretchy) and then measuring the string or ribbon with a ruler.
Keep in mind: bra sizes are measured in inches, even in Ireland.
Step 2: Measure underneath the bust for band size
Wearing no bra or a non-padded bra, run the measuring tape all the way around your back where your band sits, being careful to keep the tape level. It should be as snug as possible without digging. Take note of the measurement in inches.
Step 3: Calculate the band size
To find the band size after measuring underneath your bust, simply add 4 inches if your measurement was an even number and 3 if it’s an odd number. For example, a 31" underbust becomes a 34 band size.
The result is your band size (and the first half of your bra size)!
You can also use this handy band size chart.
Step 4: Measure the Bust Size
To measure your bust run the measuring tape around your back, just under your shoulder blades, and up around the fullest part of your bust. Round this to the nearest whole number.
Step 5: Calculate the Bra Cup Size
Lastly, subtract your band size from your bust measurement to find your cup size. The difference in inches determines your cup size (1" = A, 2" = B, 3" = C, etc.).
For example, a 39-inch bust and a 36-inch band equals 3 inches difference, therefore your bra size is 36C.
Bra Size Calculation Tips for Accurate Measurement
Getting your measurements right makes all the difference when shopping online. Here's how to improve your results.
Why Band and Bust Accuracy Matters
Small errors in measurement—like measuring over bulky clothing or holding the tape too loosely—can throw off your size completely. The band provides most of the support, so be sure it's measured snugly and level.
Common Mistakes to Avoid When Measuring
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Wearing padded or push-up bras while measuring.
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Measuring at an angle or letting the tape ride up your back.
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Forgetting to round to the nearest whole number.
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Using centimetres instead of inches (UK/IE sizing is based on inches).
How Often Should You Measure Your Bra Size?
We recommend checking your bra size every 6–12 months, or sooner if your weight, activity level, or body shape changes. Most women wear the wrong size without realising it.
Best Bra Styles for Different Breast Shapes
Once you’ve measured your bra size, the next step is finding a bra that actually suits your shape. Your breast shape—whether full, wide-set, or asymmetric—can make a big difference in how a bra fits and feels, even if the size is technically correct. Here’s how to choose styles that work best for your body.
Full & Round Breasts
Full all around? Go for bras with deep cups and smooth seams like plunge or balconette styles that contour without cutting in.
Teardrop Breasts
Fullness sits at the bottom of the bust. Opt for sweetheart necklines or half-cup bras that lift from underneath.
Wide-Set Breasts
If there’s space between your breasts, try side support bras or bras with narrower gores that gently bring them forward.
Asymmetrical Breasts
One side larger than the other? Shop for stretch-cup bras, removable padding, or fit to your larger side to avoid gaps.
Compact Breasts
Breasts that sit higher or closer to the chest wall benefit from soft triangle bras or contour styles with flexible cups.
How to Tell If Your Bra Fits Properly
A good fit doesn’t dig, gap, or shift. Use this checklist every time you try a new bra.
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Band Fit: Should be firm but comfortable—level all the way around your body. If it rides up, it’s too big.
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Cup fit: Cups should fully contain your breast tissue without spillage or wrinkling.
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Strap fit: Straps should stay put without digging into your shoulders or sliding off.
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Gore/centre panel fit: The centre panel (or gore) should lie flat against your chest. If it floats, the cup might be too small.
Shop Bras and get Free Fittings at Shaws
If you’d rather skip the tape measure and leave it to the experts, pop into one of our Shaws Department Stores across Ireland for a free, walk-in bra fitting. Our lingerie staff are trained fitters who’ll make you feel completely at ease—no appointment needed.
If you already know your size, shop our bra collection to find a range of comfortable bras that fit you.
Bra Size Chart in Inches (Ireland & UK)
Now that you’ve taken your measurements, use the chart below to find your correct bra size. This reference combines both your band size and bust measurement to help you determine your cup size and full bra size (like 34C or 36DD).
|
Band Size |
Bust Measurement (inches) |
Full Bra Size |
|
32 |
33 |
32A |
|
32 |
34 |
32B |
|
32 |
35 |
32C |
|
32 |
36 |
32D |
|
32 |
37 |
32DD |
|
34 |
35 |
34A |
|
34 |
36 |
34B |
|
34 |
37 |
34C |
|
34 |
38 |
34D |
|
34 |
39 |
34DD |
|
36 |
37 |
36A |
|
36 |
38 |
36B |
|
36 |
39 |
36C |
|
36 |
40 |
36D |
|
36 |
41 |
36DD |
|
38 |
39 |
38A |
|
38 |
40 |
38B |
|
38 |
41 |
38C |
|
38 |
42 |
38D |
|
38 |
43 |
38DD |
FAQs
How do I calculate my cup size?
Subtract your band size from your bust measurement in inches. Each inch difference = one cup size (1" = A, 2" = B, etc.).
Can I measure my bra size without a measuring tape?
Yes. Use a ribbon or string, then measure it against a ruler.
How do I know if my bra doesn’t fit?
Look for gaping cups, slipping straps, or bands that ride up. Your bra should feel supportive and smooth under clothes.
Are bra sizes in Ireland the same as the UK?
Yes. Ireland typically follows UK sizing, which is based on inches and uses cup sizes like DD, E, FF, etc.
Do bra sizes change between brands?
They can! Always check brand-specific sizing guides or try on a few different sizes if you’re unsure.
What’s the average bra size in Ireland?
While it varies by age and body type, most Irish women fall between 34B and 36C—but always go by your own measurements.