What does this calculator estimate?

It estimates a starting band number and cup-difference index from two tape measurements. Brand sizing and fit can differ.

Can I change the assumptions?

Yes. Enter values that match your situation and review the displayed assumptions and limitations before using the result.

Is the result guaranteed?

No. The result is an estimate and should be independently verified before any medical, financial, travel, sizing, fitness, or purchasing decision.

How to Measure Bra Size Calculator

Estimate a starting US bra band size and cup index from snug underbust and fullest-bust measurements entered in inches. Review the assumptions below and continue with the related guides and calculators linked on this page.

Snug underbustFullest bust

Fill in the required fields to see your result.

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Perfect for blogs, WordPress, Webflow, and business websites.

Use the primary result together with the supporting outputs. Related Calciro resources: [Clothing Size Calculator](/clothing-size-calculator), [Dress Size Calculator](/dress-size-calculator), [Body Shape Calculator](/body-shape-calculator), [How Clothing Size Conversions Work](/guides/how-to-use-clothing-size-calculator).

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How to Use This Calculator

Enter the requested values using the units shown. Keep all values consistent and review every assumption before interpreting the result.

Formula & Methodology

The calculator applies the displayed formulas directly to the entered values. Supporting outputs expose intermediate calculations rather than hiding them.

Worked example

An underbust near 32 inches and a bust near 36 inches gives a starting estimate around band 32 with a four-inch cup difference.

Bra sizing is not standardized across brands or countries. Breast shape, tissue distribution, style and personal comfort can change the best-fitting size.

Fit estimate only, not a medical assessment. Use the brand chart and try sister sizes when possible.

Related Guides

How to Measure Bra Size at Home
Learn how to use the How to Measure Bra Size Calculator, understand its assumptions and interpret the estimate.

Frequently Asked Questions

What does this calculator estimate?: It estimates a starting band number and cup-difference index from two tape measurements. Brand sizing and fit can differ.
Can I change the assumptions?: Yes. Enter values that match your situation and review the displayed assumptions and limitations before using the result.
Is the result guaranteed?: No. The result is an estimate and should be independently verified before any medical, financial, travel, sizing, fitness, or purchasing decision.

Last updated 7/22/2026