Bra Size Calculator: Find Your Perfect Fit

Our precision bra size calculator helps you determine your ideal bra size based on your unique measurements. Finding the right fit is essential for comfort, support, and confidence. This calculator provides results for the United States, United Kingdom, European Union, France, Belgium, Spain, Australia, and New Zealand sizing systems.

Enter your measurements below and click Calculate to find your bra size
Bra size measurement diagram

The bust size is the loose circumference measured around the chest over the fullest part of the breasts, while standing straight with arms to the side, and wearing a properly fitted bra.

The band or frame size is the firm circumference, fitted not tightly, measured directly underneath the breasts.

International Bra Size Converter

Use the converter below to translate your bra size between different international sizing systems.

How to Measure for the Perfect Bra Fit

Finding your correct bra size is essential for comfort, support, and confidence. Follow these steps to measure yourself accurately:

Step 1: Measure Your Band Size

Using a soft measuring tape, measure around your ribcage just under your breasts. The tape should be snug but not tight. Round to the nearest whole number. If the number is even, add 4 inches. If it's odd, add 5 inches. This is your band size. (Note: Some modern fitting methods skip the adding of inches - our calculator accommodates both approaches.)

Step 2: Measure Your Bust Size

Measure around the fullest part of your bust while wearing a non-padded bra. Keep the tape level and somewhat loose. Round to the nearest whole number.

Step 3: Calculate Your Cup Size

Subtract your band size from your bust measurement. The difference determines your cup size according to the following chart:

Difference (inches) US Cup Size UK Cup Size
Less than 1" AA AA
1" A A
2" B B
3" C C
4" D D
5" DD/E DD
6" DDD/F E
7" G F
8" H FF
9" I G
10" J GG

Understanding International Bra Size Differences

Bra sizes vary significantly between countries, making international shopping challenging. Here's a comparison of band size equivalents across different regions:

Size Category FR/BE/ES EU (EN 13402) US and UK AU, NZ
XXS 75 60 28 6
XS 80 65 30 8
S 85 70 32 10
M 90 75 34 12
L 95 80 36 14
XL 100 85 38 16
XXL 105 90 40 18

The Importance of Wearing the Right Bra Size

Studies indicate that approximately 80% of women wear incorrectly sized bras, which can lead to numerous issues including:

  • Back, neck, and shoulder pain
  • Poor posture
  • Skin irritation and chafing
  • Premature sagging of breast tissue
  • Restricted breathing
  • Reduced confidence and self-image

Wearing the correct bra size provides proper support, enhances your natural shape, improves posture, increases comfort, and can make your clothes fit better.

Signs of an Ill-Fitting Bra

You may be wearing the wrong bra size if you experience any of these common issues:

  • Band rides up in the back: Your band size is too large.
  • Straps dig into shoulders: Your band isn't providing enough support.
  • Breast tissue spills out of cups: Your cup size is too small.
  • Cups are wrinkled or gaping: Your cup size is too large.
  • Center gore doesn't lie flat against sternum: Your cup size may be too small.
  • Underwire pokes or doesn't follow breast contour: Wrong cup size or style for your breast shape.
  • Constant adjusting throughout the day: The bra doesn't fit properly.

Understanding Bra Sizing Systems Worldwide

Bra sizing varies significantly around the world, making international shopping challenging. Here's a comprehensive overview of the major sizing systems:

United States and Canada

The US and Canada use a combination of band size (measured in inches) and cup size (letters). Cup sizes typically follow the sequence: AA, A, B, C, D, DD/E, DDD/F, G, H, I, J, etc. The band size is usually the underbust measurement plus 4-5 inches, though modern fitting methods often skip this addition.

United Kingdom

The UK system is similar to the US for band sizes (in inches), but cup sizes differ after D: DD, E, F, FF, G, GG, H, HH, J, JJ, etc. This creates confusion when converting between US and UK sizes for larger cup sizes.

European Union (EN 13402)

The EU uses band sizes in centimeters, typically in 5cm increments (60, 65, 70, etc.). Cup sizes follow the sequence: AA, A, B, C, D, E, F, G, H, etc. The EN 13402 standard aims to harmonize sizing across Europe.

France, Belgium, and Spain

These countries use band sizes in centimeters, but with a different conversion from the EU standard. A 70cm EU band would be an 85cm French/Belgian/Spanish band. Cup sizes follow the same sequence as the EU.

Australia and New Zealand

Australia and New Zealand use a unique system where band sizes correspond to dress sizes (8, 10, 12, etc.). Cup sizing follows the UK system: A, B, C, D, DD, E, F, FF, G, etc.

Italy

Italy uses numbers (1, 2, 3, 4, 5) for cup sizes instead of letters, with band sizes in centimeters similar to the EU system.

Japan

Japan uses band sizes in centimeters with cup sizes A, B, C, D, E, F, G, H, etc. The sizing method differs slightly from Western approaches.

The Evolution of Bra Sizing

The modern bra sizing system has evolved significantly since its inception in the early 20th century. The first commercial standardized cup sizing was introduced in the 1930s by S.H. Camp and Company, which correlated breast sizes with letters of the alphabet (A, B, C, D). Before this innovation, bras were sized similar to clothing with small, medium, and large designations.

In the 1940s and 1950s, as bra manufacturing became more sophisticated, additional cup sizes were added to accommodate a wider range of body types. The DD cup was introduced in the 1950s, with further expansions in subsequent decades. Today, many specialty brands offer cup sizes ranging from AA to N and beyond, reflecting a more inclusive approach to body diversity.

The Science Behind Bra Sizing

Modern bra sizing incorporates anthropometric data, ergonomics, and biomechanics to create supportive garments that work with the body's natural movement. Research has shown that breast tissue is primarily supported by Cooper's ligaments, which can stretch permanently without proper support. A well-fitted bra helps distribute weight evenly, reducing strain on these ligaments and surrounding tissues.

Breast volume and shape vary significantly between individuals, even those who wear the same bra size. Factors such as age, weight fluctuations, pregnancy, breastfeeding, and hormonal changes can all affect breast size and shape throughout a person's life, necessitating regular re-measuring.

Common Bra Fitting Myths Debunked

Myth 1: Adding 4-5 inches to your underbust measurement

This outdated method dates back to when bra materials lacked elasticity. Modern bras are made with stretchier fabrics, making this addition unnecessary and often resulting in bands that are too loose. Many professional fitters now recommend using the actual underbust measurement as the starting point.

Myth 2: Cup size is absolute

Cup size is relative to band size, not an absolute volume. For example, a 34C has the same cup volume as a 36B or a 32D. This relationship is known as "sister sizing" and is useful when adjusting for comfort while maintaining the same cup volume.

Myth 3: D cups and larger are always "large" breasts

Cup size alone doesn't indicate breast size—it represents the difference between bust and band measurements. A properly fitted D cup on a small frame may appear quite different from a D cup on a larger frame.

Myth 4: Bras should be worn on the tightest hook when new

New bras should fit comfortably on the loosest hook, allowing you to tighten the band as the elastic naturally stretches over time, extending the garment's lifespan.

Specialized Bra Types and Their Sizing Considerations

Different bra styles serve various purposes and may require specific sizing considerations:

Sports Bras

These provide additional support during physical activity and often use compression, encapsulation, or a combination of both. Many sports bras use simplified sizing (S, M, L) or may require sizing up or down from your regular bra size depending on the level of compression.

Nursing Bras

Designed for breastfeeding mothers, these typically feature cups that can be easily unclasped. Experts recommend being fitted during the eighth month of pregnancy and again a few weeks postpartum as breast size fluctuates significantly during this period.

Mastectomy Bras

These specialized bras include pockets to hold breast prostheses after mastectomy surgery. Proper fitting is crucial for comfort and symmetry, and is best done by specialists trained in post-mastectomy fitting.

Minimizer Bras

Designed to reduce the projected profile of larger breasts, these redistribute breast tissue to create a smaller silhouette. They may require a different size than your standard bra.

Push-Up Bras

These enhance cleavage and lift through padding or specially designed cups. The added volume from padding may require adjusting cup size compared to non-padded styles.

The Future of Bra Sizing

The bra industry is evolving with new technologies and approaches to sizing:

  • 3D body scanning: Advanced scanning technology creates precise measurements for custom-fitted bras.
  • AI-powered sizing: Algorithms analyze photos or measurements to recommend optimal sizes across brands.
  • Size standardization efforts: Industry initiatives aim to create more consistent sizing between manufacturers.
  • Inclusive sizing: Brands are expanding size ranges to accommodate more body types.
  • Adaptive designs: Innovations for people with mobility issues or disabilities make bras more accessible.

References and Resources

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