How to Use the International Bra Size Converter

Select the bra sizing system printed on your current bra label, then choose the band size and cup size. The converter displays approximate equivalents for Australia and New Zealand, the United Kingdom, the United States, Europe, France and Spain, and Japan.

You can use the tool when:

• Shopping for bras from overseas retailers;
• Comparing Australian and UK bra sizes;
• Converting US bra sizes to Australian sizes;
• Comparing European band measurements;
• Checking French bra sizing; or
• Looking for approximate sister sizes.

Australian Bra Sizes vs UK Bra Sizes

Australian bra band sizes commonly use clothing-style numbers such as 8, 10, 12, 14 and 16, while UK bra bands commonly use measurements such as 30, 32, 34, 36 and 38.

A common approximate relationship is:

Australian Bra Sizes vs US Bra Sizes

US and UK band numbers are often similar, but cup lettering can differ after the first few cup sizes.

For example, a size labelled 34DD in one system may not always use the same cup letters in another brand or country.

European Bra Size Conversion

European bra band sizes are commonly expressed in centimetre-based numbers such as 65, 70, 75, 80 and 85.

Typical approximate conversions include:

French and Spanish Bra Sizes

French and Spanish band sizes are commonly around 15 numbers higher than the corresponding standard EU band.

For example:

• EU 70 ≈ FR/ES 85;
• EU 75 ≈ FR/ES 90;
• EU 80 ≈ FR/ES 95;
• EU 85 ≈ FR/ES 100.

Japanese Bra Sizes

Japanese bra sizing commonly uses centimetre-based band numbers similar to European sizing, such as 65, 70, 75 and 80.

Cup lettering can differ between Japanese brands, so the conversion shown by this tool should be used as a starting point rather than a guaranteed fit.

What Are Sister Bra Sizes?

Sister sizes are bra sizes with a similar approximate cup volume but a different band size.

If you move down one band size, you generally move up one cup step. If you move up one band size, you generally move down one cup step.

Sister Size Example

A commonly used example is:

These sizes are not identical in fit, but their approximate cup volume can be similar.

Why Bra Size Conversions Are Approximate

There is no perfectly universal bra sizing standard used by every brand. Differences can occur in:

• Band stretch;
• Cup shape;
• Cup depth;
• Underwire width;
• Fabric elasticity;
• Cup lettering; and
• Manufacturer-specific sizing.

For this reason, two bras carrying theoretically equivalent international sizes may still fit differently.

How Bra Band Sizes Work

The band size relates approximately to the circumference around the torso under the bust, although the exact labelling system differs by country.

For example:

• Australia commonly uses sizes such as 10, 12 and 14;
• UK and US systems commonly use 32, 34 and 36;
• EU and Japan commonly use 70, 75 and 80; and
• France and Spain commonly use 85, 90 and 95.

How Bra Cup Sizes Work

Cup size represents the relationship between bust measurement and band measurement rather than a fixed absolute breast volume.

This is why a 32D and 38D do not have the same cup volume. The cup becomes larger as the band size increases, even when the same cup letter is used.

Why Cup Letters Differ Between the UK and US

UK and US brands do not always progress through cup letters in the same way.

For example, UK sizing commonly uses double-letter cups such as DD, FF and GG, while many US brands use sequences such as DD, DDD or G.

The converter therefore maps cup sizes using a shared approximate cup-volume index rather than assuming the letters are identical.

How to Get the Best Bra Fit

A conversion tool is useful when comparing international labels, but fit should also be checked physically.

A well-fitting bra generally has:

• A band that feels firm without being painfully tight;
• Cups that contain breast tissue without obvious spilling or gaping;
• A centre gore that sits appropriately for the bra style;
• Straps that stay in place without carrying all the support; and
• An underwire position appropriate for the wearer’s shape.

Bra Size Conversion Tool Assumptions

This converter:

• Uses common approximate international band-size relationships;
• Uses a shared cup-volume index to map cup letters between systems;
• Does not guarantee identical fit between brands;
• Does not account for bra style or breast shape;
• Does not replace a manufacturer’s own size chart;
• Provides approximate sister-size relationships; and
• Is designed as a shopping and comparison aid.

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