Bra Size to Bikini Size Converter

Convert your US, UK, EU, or AU bra size to the perfect bikini top size (XS to 4XL). Get sister sizes and fit tips instantly.

Sizing Converter Settings
Recommended Bikini Size
N/A
Your bikini size conversion will appear here.
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Step-by-Step Guide

Find Swimwear Fit in 4 Easy Steps

Convert standard band and cup sizes to alphabetical bikini top sizes (XS-XXXL) instantly.

1
Choose Standard System

Select either US/Canada, UK, European (EU), or Australian sizes to align with your current underwear size.

Bands 30-44+ Cups A-H+
2
Input Band & Cup Size

Specify your active band size (e.g. 34 or 75) and cup size (e.g. C or D) inside the input selections.

Rib Band Bust Cup
3
Convert to Bikini Size

The algorithm maps the ribcage circumference and cup volume to the equivalent swimwear sizing standard.

Volumetric Mapping Swimwear Scale
4
Explore Sister Sizes

Check sister size alternatives to find swimsuit designs that feature adjustable strap backs or back ties.

Adjustable Straps Sister Fitting
Client-side processing
Auto-deleted after session
Zero server uploads
Swimwear Fitting

Bi-Directional Swim Size Converter

Find your perfect bikini top match easily. We resolve sizing confusion across multiple geographic standards so you can shop globally.

4 Sizing Zones

Converts between US/Canada, United Kingdom (UK), Europe (EU), and Australian (AU) standards.

Bikini to Bra Conversion

Easily find your target bra sizes starting from a known bikini fit (e.g. Medium or Large).

Sister sizing charts

Highlights adjacent bra sizes with the same cup capacity to explore alternative fits.

Total Privacy

Calculations run locally in the browser sandbox. No tracking, zero server calls.

FAQ

Common Questions

Why are bikini sizes labelled differently than normal bras?
Underwear bras require precise structural fits (with non-stretch wire configurations and set hooks). Swimwear materials are highly elastic, and tops often feature adjustable drawstrings, tie-backs, or halter neckbands, letting a single size (e.g., Medium) adapt to several different ribcage/cup volumes.
How do sister sizes apply to bikini purchases?
If a bikini top matches your cup size but has a loose or tight band, you can adjust. For example, if a 34C matches your volume, but the swimsuit is too loose in the chest band, you can search for a 32D (same cup volume, smaller band). Adjustable slide-straps make accommodating sister sizes simple.
What bikini style works best for small cup sizes?
For smaller cups (A-B), classic triangle tops, strapless bandeau styles, and scoop tops are ideal. Gathering, ruffles, and front-tie detailing can add the illusion of fuller volume, while push-up padding adds subtle lifting.
What styles work best for larger cup sizes (D+)?
Look for swim tops with integrated underwires, wide shoulder straps (or cross-back straps to distribute weight), and structured supportive bands. Avoid string-ties and flimsy bandeau options which lack structural support.
How do EU and US/UK sizes differ in converter calculations?
US and UK sizes measure band circumference in inches (e.g. 32, 34, 36) while EU uses metric centimeters (e.g. 70, 75, 80). EU cups also go straight (A, B, C, D, E, F) whereas US/UK systems double letters (DD, E, DDD, F, G). The converter automatically standardizes these factors.