Bra Size Calculator

Determine your correct bra band and cup size from snug underbust and full bust measurements, plus view sister sizes.

How to use this calculator

1. Measure underbust & bust.
2. Select sizing method.
3. Read band, cup, and sister sizes.

Formula & method

Band & Cup Method

Cup = Index(Bust - Band)

Modern fitting rules.

Example

30 in underbust + 34 in bust = 30D.

Key insights

• 1 inch bust-band difference = 1 cup size.

How to interpret your result

Sister Sizes

Equivalent cup volume on different bands.

Frequently asked questions

Sister size?

30D = 32C = 34B.

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