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Bra Size Calculator

Estimate a starting band and cup label from underbust and bust measurements.

Bra Size Calculator Inputs

Results computed instantly — your data never leaves your device.

Bra Size Calculator Results

Real-Time

Estimated size

34D

Cup difference

4.0 inches

100% Client-SidePrivate & Secure

How to Use the Bra Size Calculator

  1. 1

    Enter underbust measurement in inches.

  2. 2

    Enter bust measurement in inches.

  3. 3

    Review the approximate band and cup label.

  4. 4

    Check the brand’s own size chart and fit because sizing systems vary.

Formula & Mathematical Basis

Band = max(28, nearest even underbust); cup index = round(max(0, bust − band)).

Variable Key

underbust

Measurement around the rib cage in inches

bust

Measurement around the fullest bust point in inches

📝 This is a simplified starting estimate using one band/cup convention; it is not a medical or guaranteed garment-size determination.

Step-by-Step Examples

1

Approximate fit starting point

Scenario: Enter 34 inches underbust and 38 inches bust.

  1. 1.Round the band convention to 34.
  2. 2.Subtract band from bust for a 4-inch difference.
  3. 3.Map the difference to the simplified cup sequence.
  4. 4.Confirm against the brand and garment fit.
✅ The starting estimate is 34D under this simplified model.

Practical Use Cases

  • Create a first-pass sizing starting point.
  • Compare measurements before checking a retailer chart.

Common Pitfalls

  • Measuring over thick clothing.
  • Assuming brands use the same cup progression.
  • Treating a starting estimate as a guaranteed fit.

Frequently Asked Questions

Is the result universal?

No; sizing systems and fit vary by brand, style, and region.

Is this a health assessment?

No; it is an approximate clothing-size helper only.

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