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Bra Size Calculator

Find your bra size from your underbust and bust measurements, with US, UK, EU, French and Australian sizes and sister sizes. Free bra size calculator.

US bra size
32D
UK size
32D
EU size
70D
French size
85D
Australian size
10D
Sister sizes (US)
30DD, 34C

Brands fit differently, so treat this as a starting size and try the sister sizes too.

How to work out your bra size

Your band size comes from the measurement around your ribcage, just under the bust, rounded to an even number. Your cup size is the difference between your bust and the band: each inch is one cup size. An underbust of 31 inches gives a 32 band; a 36-inch bust is 4 inches more, a D cup, so you're a 32D (UK 32D, EU 70D). Cup letters differ by country after D, so the calculator shows every system. Sister sizes, one band up and one cup down, hold the same volume.

How to use it

  1. 1

    Measure your underbust

    Snugly around your ribcage, directly under the bust.

  2. 2

    Measure your bust

    Loosely around the fullest part, with the tape level.

  3. 3

    Read your size

    In US, UK, EU, French and Australian sizes, plus sister sizes.

Frequently asked questions

How do I measure for a bra?

Wear an unpadded bra. Measure under the bust (snug) and around the fullest part (loose), keeping the tape level.

What is a sister size?

A size with the same cup volume on a different band: 34C, 32D and 36B are sister sizes.

Why does my size differ between brands?

Brands cut differently. Use this as a starting point and try the sister sizes too.

Are my measurements stored?

No. Nothing leaves your browser.

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