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Bras

Cup size

The letter in a bra size, such as the C in 34C, based on the difference between the bust and underbust measurements.

In the common US and UK method, each inch of difference between the bust measurement and the underbust measurement adds one cup size: about 1 inch is an A, 2 inches a B, 3 inches a C, and so on.

Cup size depends on the band: a 32D and a 34C hold a similar cup volume. These are called sister sizes. Letters after D differ between countries and brands.

Drawing showing where to measure cup size, labelled BBCup size
How to measure

Measurement B: Measure this part straight across at its widest point.

Related terms

Band sizeBust

Size charts that use cup size

2 templates
Women's Bra Size Chart
Underwear · 30 – 40
Women's Bikini Top Size Chart
Swimwear · XS – XXL
Add a clear size chart to your Shopify store

Jotly adds a size chart with a labelled how-to-measure drawing and a cm/in switch to your Shopify product pages.

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