Bra Size Calculator | Band, Cup and Region Conversion

Calculate an estimated bra size from underbust and bust measurements, with US, UK, EU, and AU/NZ size references.

Measurement Unit

Underbust Measurement

Bust Measurement

Estimated Bra Size

Europe (EU)

United States (US)

United Kingdom (UK)

Australia / NZ

Calculate Bra Size from Bust Measurements

Enter underbust and bust measurements to estimate band size, cup size, and regional sizing references for US, UK, EU, and AU/NZ systems.

Fit Depends on More Than Numbers

Shape, brand, fabric, style, strap position, and personal comfort can change the best size. Use the result as a fitting starting point.

When Bra Size Estimates Help

Use it before online shopping, comparing regional size charts, checking measurement changes, or preparing a first fitting size to try.

About This Tool

Bra Size Calculator determines your bra size from band and bust measurements in centimetres or inches and converts between UK, US, EU, and international sizing systems.

Good Times to Use It

Use this when buying a bra online and you are unsure of your size, when converting between sizing systems across different brands, or after a significant change in body shape.

Step by Step

Measure your band snugly under your bust.
Measure your bust at the fullest point.
Enter both measurements and select your unit.
Click Calculate to see your size across different sizing systems.

FAQ

Why do bra sizes vary between brands?

Brands manufacture to their own templates. A 34B in one brand may fit differently than a 34B in another. Use measurements as a starting point and check fit in person.

What is sister sizing?

Sister sizes are adjacent sizes with the same cup volume but different band widths. Going up one band and down one cup gives an equivalent fit.

How often should I remeasure?

Remeasure whenever weight changes significantly, after pregnancy, or if current bras feel uncomfortable.

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