Conversions
Length converter
Convert metres into common length units.
Calculators / Everyday / Bra size estimate
Bra size estimate calculator
Estimate a band and cup label from underbust and bust measurements.
On this page
Estimated starting size34D
Rounded difference4inches
Calculator controls
How to calculate
Estimate a band and cup label from underbust and bust measurements.
Round the underbust to an even band size; cup index is the rounded bust-minus-band difference.
Worked example
Underbust circumference (inches): 34; Full bust circumference (inches): 38.
Estimated starting size: 34D ; Rounded difference: 4 inches.
Assumptions and limits
Sizing systems and brands differ substantially. Treat this as a starting point and use the manufacturer’s fitting chart.
Results are rounded for display; calculations use unrounded values. Read our calculation methodology.
Understanding the result
Estimate a band and cup label from underbust and bust measurements. The displayed figures use the inputs and formula shown on this page.
When this tool is useful
Use the bra size estimate to compare a scenario, check an estimate, or verify a manual calculation.
Understanding your inputs
| Input | What to enter |
|---|---|
| Underbust circumference (inches) | Enter a number of at least 0.000001 and no more than 1000000000000. |
| Full bust circumference (inches) | Enter a number of at least 0.000001 and no more than 1000000000000. |
Frequently asked questions
What should I check before using the bra size estimate result?
Sizing systems and brands differ substantially. Treat this as a starting point and use the manufacturer’s fitting chart.
Is this bra size estimate result exact?
It is exact for the stated mathematical model and entered values. Real-world results can differ when rates, timing, fees, definitions or measurement conditions differ.