Bra Size Converter (US, UK, EU, FR)
Convert your bra size between major sizing systems in seconds.
How this bra size conversion calculator works
Bra sizing is not universal. A size that looks familiar in one region can be labeled very differently in another. This calculator converts both band size and cup size between common systems: US, UK, EU, and FR/ES. Enter your current size, choose a target system, and get an equivalent result instantly.
The conversion is based on standard size progression. Because brands may have slightly different grading rules, treat the result as a strong starting point, then fine-tune based on fit.
Supported size systems
- US: Band sizes in even numbers (30, 32, 34...) with cups like D, DD, DDD, G...
- UK: Band sizes in even numbers with UK cup progression (D, DD, E, F, FF...)
- EU: Band sizes typically in 5-step increments (65, 70, 75...) with single-letter cups
- FR/ES: Similar to EU cup labeling but with higher band numbers (85, 90, 95...)
Quick bra size conversion chart
Here are common equivalents to help you sanity-check your result:
| US | UK | EU | FR/ES |
|---|---|---|---|
| 32D | 32D | 70D | 85D |
| 34DD | 34DD | 75E | 90E |
| 34DDD | 34E | 75F | 90F |
| 36G | 36F | 80G | 95G |
| 38H | 38FF | 85H | 100H |
How to measure for better accuracy
1) Measure your underbust (band)
Wrap a soft tape snugly around your ribcage directly under your bust. Keep it level all the way around. This determines your band starting point.
2) Measure your full bust
Measure around the fullest part of your bust while wearing a non-padded bra. Keep the tape comfortably level and avoid pulling too tight.
3) Use the difference to estimate cup volume
The difference between full bust and underbust contributes to cup size. Once you have a solid size in one system, this calculator helps convert it for international brands and online shopping.
Sister sizes: why nearby sizes can still fit
Sister sizes keep roughly the same cup volume while changing band tightness. For example, if 34DD feels tight in the band, 36D may feel more comfortable; if 34DD feels loose in the band, 32E may work better.
The calculator also suggests nearby sister-size equivalents in your target system so you can compare options quickly.
Important fit tips for online bra shopping
- Check each brand's own size chart before checkout.
- Read reviews for comments about cups running small or bands running tight.
- Prioritize fit signs: band support, center gore tack, cup containment, and strap comfort.
- When in doubt, order two neighboring sister sizes and keep the better fit.
Frequently asked questions
Is US cup sizing the same as UK sizing?
No. They match at smaller cups, then diverge after D. UK uses double-letter steps (DD, FF, GG), while US often uses DD and DDD before moving to G, H, I.
Why does one bra fit in one brand but not another?
Different wire widths, cup shapes, and elastic tension can change fit even when the label is the same.
Can this calculator replace a professional fitting?
It is a reliable conversion tool, but a fitting (or careful trial at home) is still best for perfect comfort and support.