Private, international and easy to understand
Find a Better Starting Size in Minutes
Enter your measurements to estimate your bra size, compare UK, US, EU and French sizing, and understand what to try next. Your result is a starting point - not a promise that every bra with the same label will fit the same way.
- Private by Default
- International Sizing
- Explained Starting Range
- No Account Required
Calculate a starting bra size
Enter two measurements for a quick estimate, or switch to advanced mode for a wider, more precise range.
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Advanced fit analysis
Six measurements give a comfort range for the band and a more reliable cup estimate.
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Why Your Result May Look Surprising
A smaller band and a larger cup letter can look dramatically different from the size you currently wear. That does not automatically mean the result is too large. Cup letters are relative to band size, so a D cup is not one fixed volume.
Cup Letters Are Relative
The same letter means a different volume on every band size - it's a relationship, not a fixed measurement.
A Loose Band Can Hide a Small Cup
If the band isn't doing its share of the work, the cups can look and feel wrong even at the right volume.
Shape Can Change How a Cup Looks and Feels
Projection, fullness and root width all affect fit independently of the size number.
Choose the Right Tool for Your Next Question
International Converter
Already know a size? See it in UK, US, EU, French, AU/NZ and JP labels instantly.
Sister Size Calculator
Cups fit but the band doesn't? Find the nearest size with the same cup volume.
Bra Fit Checker
Already own the bra? Answer a few questions to see what's actually going on.
Bra Size Charts
Prefer to browse? Compare every system side by side in one reference table.
Check the Fit, Not Only the Label
- Band sits level
- Cups contain the tissue without cutting in
- Centre panel sits as close to the chest as the style and anatomy allow
- Wires do not rest on breast tissue
- Straps stay secure without carrying all the support
Understand What the Number and Letter Mean
The band number is your underbust measurement rounded to the nearest even size. The cup letter describes the difference between your bust and band - a relative volume, not a universal size. That's why the same cup volume can carry a different letter on a different band:
32DD → 34D → 36C
Similar cup volume, different band fit.
Measurements Give a Starting Point. Fit Gives the Answer.
A calculator cannot see cup depth, wire width, fabric stretch or how a particular style sits on your body. We therefore show a starting range, explain the calculation and give you a fit check instead of claiming one guaranteed size.
Ready to Measure?
Use the quick calculator for a fast estimate or the advanced mode when you want a more detailed starting range.