Bra Size Calculator

Bra Size Calculator

PROFESSIONAL BRA SIZING TOOL WITH AI TECHNOLOGY

HOW TO MEASURE YOUR BRA SIZE AT HOME

Our AI-powered bra size calculator takes just 60 seconds and provides accurate sizing for UK, EU, and US measurements. 
Whether you're measuring for the first time or checking your current size, our tool helps you get the support and comfort you deserve so you can move through your world in comfort.

HOW TO MEASURE YOUR BRA SIZE: STEP BY STEP GUIDE

What You'll Need:

•Soft measuring tape (fabric, not metal)

•Mirror (optional but helpful for accuracy)

•Well-fitting non-padded bra or no bra at all

To discover your bra size yourself, simply follow our step-by-step guide. All you need is a measuring tape and you are ready to go.

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Measure Your Underbust (Band)

Measure Your Bust

What is your current Cup Size?
How does your band feel?
How do your cups feel?
How do your straps sit?

Wrap the tape snugly around your ribcage, directly under your breasts. Keep the tape level and breathe normally. Round to the nearest even inch for UK sizing (e.g., 34, 36) or nearest centimetre for metric measurements.

If you don't have a tape measure, enter the approximate size of your preferred bra.

Wrap the tape around the fullest part of your chest at nipple level.

Keep the tape straight, parallel to the floor, and avoid pulling too tight. Relax your arms naturally by your sides.

Your size is:
inch
cm
slide the measuring tape

The right bra is all about the one that fits your perfectly weel, when it comes to the fit of the bra there are three things that you need to consider:

The Right Cup

The Right Cup

Your breasts should sit fully inside the cups without bulging or overflow. If you see bulging at the top or sides, go up a cup. If there is extra space or wrinkling, go down a cup. The underwire (if present) should lie flat against your chest, not press into tissue. A well-fitted cup gives smooth support and a natural shape.

The Right Band

The Right Band

Most of your bra’s support comes from the band, so it should sit level and snug around your ribcage. If it rides up your back, the band is too loose. Go down a size. You should be able to fit two fingers comfortably under the band, but not more. A secure band prevents shifting, ensures lift, and keeps the bra in place throughout the day.

The Right Straps

The Right Straps

Straps should rest comfortably on your shoulders without digging in or slipping off. If tightening doesn’t help, the cups are the wrong size. Go larger if straps dig; go smaller if they slip. Wide-set or adjustable straps can improve comfort. Remember, straps provide balance, not full support. The band does most of the work. Proper strap position keeps your bra stable and comfortable.

FAQ

FAQ

Discover Triumph Bras in Your Perfect Size

FIND YOUR PERFECT
BRA STYLE

Now that you know your true bra size, discover
which bra style suits your body type, lifestyle,
and needs. Every body is unique, and so is the
bra that feels right.

DIFFERENT STYLES FOR EVERYDAY COMFORT
Once you know your size, explore sloggi’s bras designed for every shape and style. Each recommended bra comes in your calculated size (band + cup) to ensure a great fit. Click “Shop My Size” or select a category above to see hand-picked sloggi bras for your size and style. 

SIZING & MEASUREMENTS PER CATEGORY

Click the category to see the sizing chart

FREQUENTLY ASKED QUESTIONS ABOUT BRA SIZING

  • What bra size am I?

    Your bra size consists of two components: a band size (the number) and a cup size (the letter). The band size is your underbust measurement, while the cup size is determined by the difference between your bust and underbust measurements.


    To find your bra size:

    1. Measure your underbust (this becomes your band size)

    2. Measure your bust at the fullest point

    3. Subtract band from bust to determine cup size


    For example, if your underbust is 32 inches and your bust is 36 inches, the 4-inch difference means you're a D cup—so your size is 32D.


    Use our free bra size calculator above for instant, accurate results. Simply enter your measurements and get your UK, EU, and US sizes in seconds.

  • How do I know my bra size?

    The most accurate way to know your bra size is to measure yourself at home using a soft measuring tape. Follow these simple steps:

    Quick Method

    1. Underbust measurement = your band size

    2. Bust measurement (fullest part) minus band size = cup size difference

    3. Use the cup size chart to convert the difference to a letter


    Signs you're wearing the wrong bra size:

    • Band rides up at the back

    • Cups gap or overflow at the top

    • Breast tissue spills out at the sides

    • Straps constantly dig into your shoulders

    • You need to adjust your bra throughout the day


    If you're experiencing any of these issues, it's time to remeasure. Our AI-powered bra size calculator provides professional accuracy in under 60 seconds.

  • What is the biggest/largest bra size?

    Bra sizes extend far beyond the commonly known DD cup. At sloggi, we offer an extensive size range so everyone can find their perfect fit:


    Our Size Range:

    • UK cup sizes: Up to K cup

    • Band sizes: 28-44 inches (60-100cm EU)


    Common large cup sizes include: DD, E, F, FF, G, GG, H, HH, J, JJ, K


    Important features for larger cup sizes:

    • Wide, cushioned straps to distribute weight

    • Reinforced underwire for enhanced support

    • Multi-hook back closures for secure fit

    • Side support panels to prevent spillage


    Remember, cup size is relative to band size. A 32DD has a different volume than a 38DD, which is why accurate measurement of both dimensions is crucial. Use our calculator to find your exact size, whatever your cup size.

  • How to measure your bra size at home?

    Measuring your bra size at home is simple and takes just a few minutes. Here's exactly what to do:


    What You Need:

    • Soft fabric measuring tape (not rigid metal)

    • Mirror (helpful but optional)

    • Someone to help (optional but can improve accuracy)


    Step-by-Step Home Measurement:

    1. Wear the right bra: Put on a non-padded, well-fitting bra or no bra at all

    2. Measure band size: Wrap tape snugly around your ribcage, just under your breasts. Keep it level and parallel to the floor

    3. Measure bust size: Measure around the fullest part of your bust, usually at nipple level

    4. Calculate cup size: Subtract band measurement from bust measurement


    Pro Tips for Accuracy:

    • Stand in front of a mirror to ensure tape is level

    • Don't hold your breath while measuring

    • Don't pull the tape too tight, it should be snug but comfortable

    • Take measurements 2-3 times to confirm consistency

    • Measure at the same time of day (bust size can fluctuate)


    Our detailed measuring guide above includes visual aids and a step-by-step calculator to help you get precise measurements every time. And remember, not everyone who wears a bra identifies in the same way—this guide is here for every body.

  • What does bra cup size mean?

    Cup size represents the volume difference between your bust and band measurements. Each cup letter corresponds to a specific difference in inches or centimeters.


    How Cup Sizes Work:

    • Each cup size = approximately 1 inch (2.5cm) difference

    • A cup = 1" difference

    • B cup = 2" difference

    • C cup = 3" difference

    • D cup = 4" difference

    • DD/E cup = 5" difference

    • And so on...


    Real Example:

    • Band measurement: 34 inches

    • Bust measurement: 37 inches

    • Difference: 3 inches = C cup

    • Your bra size: 34C


    Important to Know:

    Cup size is NOT absolute—it's relative to your band size. This means:

    • A 34C has a different cup volume than a 36C

    • A 34C and 36B have the same cup volume (sister sizes)

    • Both measurements work together to determine fit

    This is why you need to measure both your band and bust to find the bra size that truly fits you. Our calculator does all the math for you automatically.

  • What is my bra size UK?

    UK bra sizes follow a specific format: [Band Number][Cup Letter]


    UK Sizing System Explained:


    Band sizes:

    Even numbers from 28 to 44+ (28, 30, 32, 34, 36, 38, 40, 42, 44)


    Cup sizes:

    AA, A, B, C, D, DD, E, F, FF, G, GG, H, HH, J, JJ, K


    Key Differences Between Sizing Systems:


    UK vs US:

    • Band sizes are similar but cup letters differ after D

    • UK DD = US E cup

    • UK E = US DDD or F cup

    • Generally UK sizing is more consistent


    UK vs EU:

    • EU uses centimeters for band size

    • UK 32 = EU 70

    • UK 34 = EU 75

    • UK 36 = EU 80

    • Cup letters generally match between UK and EU


    To find your accurate UK bra size, use our calculator tool above. It automatically converts between UK, US, and EU sizing so you can shop confidently from any brand or region.

  • How to measure bra size in cm?

    If you prefer metric measurements, here's how to measure your bra size in centimeters:


    Band Size (cm):

    1. Measure your underbust in centimeters

    2. Round to the nearest 5cm increment

    3. Common EU band sizes: 60, 65, 70, 75, 80, 85, 90, 95, 100cm


    Bust Measurement (cm):

    1. Measure around the fullest part of your bust in centimeters

    2. Keep the tape level and snug but not tight


    Calculate Cup Size:

    Subtract band measurement from bust measurement:


    Difference (cm) Cup Size


    10-12cm - A

    12-14cm - B

    14-16cm - C

    16-18cm - D

    18-20cm - DD/E

    20-22cm - F

    22-24cm - FF

    24-26cm - G


    Example Calculation:

    • Band: 75cm

    • Bust: 91cm

    • Difference: 16cm = C cup

    • Your size: 75C (EU) or 34C (UK)


    Our bra size calculator works with both inches and centimeters. Simply select your preferred unit of measurement and enter your numbers for instant results.

  • What are bra sister sizes?

    Sister sizes are different bra sizes that have the same cup volume. When you go up one band size, you go down one cup size to maintain the same volume (and vice versa).


    How Sister Sizes Work:


    If you wear a 34C, your sister sizes are:

    • 32D (smaller band, larger cup letter)

    • 36B (larger band, smaller cup letter)


    All three sizes (32D, 34C, 36B) have the same cup volume, but the proportions and fit feel different due to the band size.


    When to Use Sister Sizes:

    • Band too tight? Try the next band size up + one cup size down

    • Band too loose? Try the next band size down + one cup size up

    • Your size is out of stock? Sister sizes are often available

    • Between sizes? Sister sizing helps fine-tune your fit


    Sister Size Chart Examples:

    Your Size

    Smaller Band

    Larger Band

    32C

    30D

    34B

    34D

    32DD

    36C

    36DD

    34E

    38D

    38E

    36F

    40DD


    Important Note: While sister sizes have the same cup volume, they fit differently around your body. The band provides most of the support, so getting the right band size is crucial for comfort and proper lift. If you're between sizes, always try both options to see which feels better.

  • What is the average UK bra size?

    The average bra size in the UK has changed significantly over the past few decades. Current statistics show that the average UK bra size is approximately 36D.


    UK Bra Size Trends:

    • 1950s average: 34B

    • 1990s average: 34C

    • 2010s average: 36C

    • Current average: 36D


    Why Has the Average Changed?

    Several factors contribute to the increasing average:

    • Improved measuring techniques and awareness

    • Better access to proper bra fittings

    • Changes in lifestyle and nutrition

    • Greater availability of larger cup sizes


    But Averages Don't Tell Your Story:

    Every body is unique. The "average" size doesn't mean it's the "right" size for you. Factors that influence your bra size include:


    • Genetics and body type

    • Weight fluctuations

    • Pregnancy and breastfeeding

    • Age and hormonal changes

    • Overall health and fitness


    And not everyone who wears a bra identifies in the same way, instead of comparing yourself to statistics, focus on finding YOUR perfect fit. Our bra size calculator is designed to give you accurate, personalized measurements regardless of what the average might be.

  • What does the number in bra size mean?

    The number in your bra size represents your band size—the measurement around your ribcage directly under your breasts.


    Understanding Band Size Numbers:


    UK/US Band Sizes:

    • Numbers represent inches around your underbust

    • Always even numbers: 28, 30, 32, 34, 36, 38, 40, 42, 44

    • Example: Size 34D means 34-inch underbust, D cup


    EU Band Sizes:

    • Numbers represent centimeters around your underbust

    • Increments of 5cm: 60, 65, 70, 75, 80, 85, 90, 95, 100

    • Example: Size 75C means 75cm underbust, C cup


    Why Band Size Matters:

    The band provides 80-90% of your bra's support—not the straps! A correctly fitted band should:

    • Sit level all the way around (not ride up at the back)

    • Feel snug but not restrictively tight

    • Stay in place when you move

    • Allow you to fit two fingers underneath comfortably


    Common Band Size Mistakes:

    • Wearing band too loose (causes lack of support)

    • Wearing band too tight (causes discomfort and bulging)

    • Not adjusting band as weight changes


    The band is the foundation of proper bra fit. Get this measurement right first, then determine your cup size. Our calculator helps you get both dimensions accurately.

Find Your Fit

sloggi Size Chart

European Size
Size
UK Size
Waist circumference (cm)
Hip circumference (cm)
FREE Evolve
32 34 36 38 40 42 44 46 48 50 52 54 56
XS XS S S M M L L XL XL XXL XXL XXL
4 6 8 10 12 14 16 18 20 22 24 26 28
56‑59 60‑63 64‑67 68‑72 73‑77 78‑82 83‑87 88‑92 93‑97 98‑102 103‑107 108‑112 113‑117
82‑85 86‑89 90‑93 94‑98 99‑103 104‑108 109‑113 114‑118 119‑123 124‑128 129‑133 134‑138 139‑143
1 1 1 1 1 1 2 2 2 2

How to measure your bra size

Helps you to measure yourself, measuring tape required