Lingerie sizes: how to make sense of them?

Why are lingerie sizes so confusing?

A bra size consists of two elements—the band size (underbust measurement) and the cup size—and each country uses a different system to express them. A French 85C does not correspond to a UK 34C—even though the letters are identical, the volumes are different.

This confusion is compounded by the fact that brands use their own size charts, which may differ from national standards. The only reliable way to find the right size is to start with your measurements in centimeters and compare them with the specific brand's size chart.

Bra sizing systems

French / European system (FR/EU)

The band is expressed in centimeters—80, 85, 90, 95, 100, etc. Generally, the band size corresponds to the measured underbust rounded up to the nearest ten—but this rule varies by manufacturer. Cup sizes are expressed in letters: A, B, C, D, E, F, G…

British system (UK)

The band is expressed in inches—30, 32, 34, 36, 38, etc. Cup sizes range from A to K or higher. A D cup on a 32 UK band represents a different volume from a D cup on a 36 UK band—the cup volume is not absolute; it depends on the band size.

American system (US)

Similar to the British system—band in inches, cups in letters. Cup size equivalents may differ slightly from the UK system depending on the brand.

Asian system (Japan, China, Korea)

Bands are expressed in centimeters, but the calculation differs. In Korea, the difference between bust and underbust measurements is 2.5 cm per cup, whereas in the United Kingdom this difference is 1 inch (2.54 cm). Japanese size 70 corresponds to an underbust measurement of 68–72 cm. Asian brands may fit differently from European brands, even for sizes that are theoretically equivalent.

Band size conversion chart

Note: these conversions are indicative — exact values vary by manufacturer. Always consult the brand’s specific size chart before making a purchase.

Cup size conversion chart

A French E cup corresponds to a British DD cup — beware of confusion when shopping on foreign websites.

Bottom sizes: briefs, thongs, and boyshorts

Bottom sizes are based primarily on the hip measurement. Systems differ here as well:

These equivalences are indicative — Spanish and Eastern European brands (very common in sexy lingerie) may use different sizing charts. Always check the brand’s specific size chart.

The principle of sister sizes

The concept of sister sizes is not widely known but is very useful. If you cannot find your exact size, a sister size offers the same cup volume with a different band size:

• Go up one band size + down one cup size = the same breast volume (e.g., 85C = 90B = 80D)
• Go down one band size + up one cup size = the same breast volume

Sister sizes help you find a comfortable fit when your exact size is unavailable — but they do not replace the ideal size in terms of support.

How to interpret sizes by brand

French and European brands

Use the FR size directly based on your measurements. Check the specific brand’s size chart — some French brands run smaller or larger than standard.

British and American brands

Convert the back measurement to inches (divide by 2.54) to obtain the UK/US band size. Be careful with cup sizing — a French E = British DD = American DDD, depending on the brand.

Spanish brands

Very common in sexy lingerie — they often use standard European sizes but may have more fitted cuts. Check customer reviews on sizing.

Asian brands

Generally run smaller than European brands. You will often need to choose one size up from your usual size.

Common mistakes to avoid

• Confuse the FR and UK systems: a French 90C does not correspond to a British 36C — bands are in cm for FR and in inches for UK.
• Believe that the cup is universal: a D cup does not represent the same volume depending on the band size — a D/80 is smaller than a D/100.
• Ignore cups beyond D: cup letters do not stop at D. E, F, G, and H cups exist and correspond to real volumes — women with larger breasts often need a smaller band and a larger cup than the size they wear.
• Rely only on the generic size (S/M/L): for bras, the generic size is too imprecise. Always use the full size (band + cup).
• Do not check the brand's size chart: size charts vary — an 85C Simone Pérèle is not identical to an 85C Aubade.

In brief: how to find your way around lingerie sizes

• Always start with your measurements in cm — never with a usual size
• FR system: band in cm (80, 85, 90…) + cup in letters (A, B, C, D, E, F…)
• UK/US system: band in inches (32, 34, 36…) + different cup sizing (E FR = DD UK)
• Asian brands: generally run smaller — choose one size up
• Sister sizes: same volume, different band (85C = 90B = 80D)
• Always consult the size chart specific to each brand