Bra Sister Size Calculator

Find your bra sister sizes for a tighter or looser band with equivalent cup volume.

Inputs

Results

Tighter Band

32D

Looser Band

36B

How to use this calculator
  1. 1Enter your current US band and cup.
  2. 2Try the tighter-band/larger-cup or looser-band/smaller-cup option.
  3. 3Sister sizes share cup volume but change band fit.
Frequently Asked Questions
How to Use

About the Bra Sister Size Calculator

What it calculates

Finds sister sizes — same cup volume with a tighter or looser band (e.g., 34C ↔ 32D ↔ 36B).

When to use it

Use when your band feels too tight but the cup fits, or vice versa.

Example

34C sister sizes: tighter band 32D, looser band 36B.

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