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Bra sizing combines a band measurement and a cup measurement, calculated from the difference between your underbust and bust measurements.
This calculator estimates your band and cup size from those two measurements using a standard, widely published sizing formula.
How it works
Enter your band (underbust) and bust measurements in inches. The calculator rounds the band measurement and adds 4 (if even) or 5 (if odd) to find the band size, then compares the bust measurement to the band size to determine the cup letter.
- Enter band (underbust) measurement (in).
- Enter bust measurement (in).
- Click Calculate to see your results.
Examples
32 in band, 36 in bust
A 32-inch underbust and 36-inch bust measurement produces an estimated 36AA using this sizing method.
Who should use it
- Getting a starting size estimate before shopping online.
- Rechecking your size after a body change (weight change, pregnancy, etc.).
Industry applications
- Apparel and lingerie retail
- Personal shopping and fitting services
Advantages
- Uses a widely published, standard bra sizing formula.
- Quick two-measurement estimate.
Limitations
- Sizing conventions vary by brand and by fitting method — treat the result as a starting estimate.
Common mistakes to avoid
- Measuring over a padded or ill-fitting bra rather than measuring directly against the body or in a well-fitting bra.
- Pulling the tape measure too tight, which understates both measurements.
Best practices
- Get professionally fitted at least once and use that result to calibrate how this calculator's formula compares for your body and preferred brands.
Tips
- Re-measure and recalculate periodically — bra size can change with weight fluctuations, pregnancy, and even the specific bra style.