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Apparel & SizingInternational Sizing & Sister Sizes

Bra Size Calculator

Accurately calculate your proper bra size based on your bust and underbust ribcage measurements. Convert sizing across US, UK, EU, France, and Australia, and discover your sister sizes.

Modify the values and click the calculate button to use

Body Measurements

Fullest point
Directly under breasts
Quick Presets:
Estimated Bra Size Result

Your Size: 34D (US / CA)

Bust: 38" | Underbust: 34" (Difference: 4" = Cup D)
International Sizing Matrix:
US & Canada
34D
United Kingdom
34D
EU (EN 13402)
85D
Australia / NZ
12D
Sister Sizes (Equivalent Cup Volume):
Tighter Band (Sister Down):32DD/E
Looser Band (Sister Up):36C
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How to Measure Your Bra Size Accurately

To find your accurate bra size, use a soft measuring tape and take two measurements:

  1. Underbust (Band Size): Wrap the tape snugly around your ribcage directly beneath your breasts. Keep the tape parallel to the floor. Round to the nearest even whole number.
  2. Overbust (Bust Size): Measure loosely around the fullest part of your chest while standing straight with arms relaxed at your sides.
  3. Calculate Cup Letter: Subtract your underbust measurement from your bust measurement. Each 1-inch increment corresponds to one cup size step.

Bust to Band Difference Cup Size Scale

0" difference:Cup AA
1" difference:Cup A
2" difference:Cup B
3" difference:Cup C
4" difference:Cup D
5" difference:Cup DD / E
6" difference:Cup DDD / F
7" difference:Cup G
8" difference:Cup H
9" difference:Cup I
10" difference:Cup J