Bra Size Chart: Band, Bust, Cup Size, US, UK & EU Guide
Find bra size from underbust, bust and cup difference with US, UK and EU band and cup conversion notes.
Bra band size chart
Start with underbust to estimate band size, then combine it with cup difference.
| Snug underbust | US band | UK band | EU band | Fit note |
|---|---|---|---|---|
| 26-27 in / 66-69 cm | 30 | 30 | 65 | Try 28 only if the brand runs stretchy |
| 28-29 in / 71-74 cm | 32 | 32 | 70 | Common small-band range |
| 30-31 in / 76-79 cm | 34 | 34 | 75 | Common medium-band range |
| 32-33 in / 81-84 cm | 36 | 36 | 80 | Check band tension on the loosest hook |
| 34-35 in / 86-89 cm | 38 | 38 | 85 | Sister size down if the band rides up |
| 36-37 in / 91-94 cm | 40 | 40 | 90 | Extended band range |
| 38-39 in / 97-99 cm | 42 | 42 | 95 | Extended band range |
| 40-41 in / 102-104 cm | 44 | 44 | 100 | Extended band range |
Band methods vary by calculator and brand. A band should sit level and firm on the loosest hook when new.
Cup size chart by bust minus band difference
Subtract band/underbust reference from full bust to estimate cup letter. Cup labels vary by country.
| Difference | US cup | UK cup | EU cup | Fit note |
|---|---|---|---|---|
| 1 in / 2.5 cm | A | A | A | Small difference between bust and band |
| 2 in / 5 cm | B | B | B | Common starter cup difference |
| 3 in / 7.5 cm | C | C | C | Medium cup difference |
| 4 in / 10 cm | D | D | D | Check gore and wire placement |
| 5 in / 12.5 cm | DD / E | DD | E | Labels diverge by region |
| 6 in / 15 cm | DDD / F | E | F | US and UK labels may not match |
| 7 in / 18 cm | G | F | G | Confirm brand cup progression |
| 8 in / 20 cm | H | FF | H | Often needs brand-specific fit notes |
| 9 in / 23 cm | I | G | I | Extended cup range |
| 10 in / 25 cm | J | GG | J | Extended cup range |
Cup letters are not absolute volume. The same cup letter changes volume when the band size changes.
Bra sister size examples
Sister sizes keep similar cup volume while changing band tension.
| Starting size | Tighter band sister size | Looser band sister size | When to use it |
|---|---|---|---|
| 32C | 30D | 34B | Use when cup volume is close but the band fit is wrong |
| 34D | 32DD / 32E | 36C | Down a band usually means up a cup letter |
| 36DD | 34DDD / 34E | 38D | Useful for trying nearby stock sizes |
| 38G | 36H or UK 36FF | 40DDD / 40F | Always verify US vs UK labels |
Use sister sizes for small adjustments, not as a replacement for checking wire width, cup depth, and strap placement.
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Calculate band and cup
Measure underbust and bust, then convert the difference into cup guidance.
Women apparel connections
Use bust and bra fit checks when choosing fitted tops, dresses and jackets.
Measurement workflow
Confirm tape placement before trusting band, bust, waist or hip labels.
How to measure before choosing a size
Related size charts
More in Bra Fit
Bra Size Calculator
Calculator searchers want a direct formula, not only a chart, plus reassurance about sister sizes and regional cup labels.
Cup Size Chart
Cup size users want to decode letters such as DD, DDD, E and F and understand that cup letters change with band size.
Bust Size Chart
Bust size searchers often need measurement instructions and a bridge from full bust to dresses, jackets, shirts and bra cups.
FAQ
How do I calculate bra size?
Measure snug underbust for band, measure full bust, subtract band reference from bust, and map the difference to a cup letter.
Is a D cup always the same size?
No. Cup volume changes with band size, so 32D, 34D and 36D are different volumes.
What if the band rides up?
Try a smaller band or a sister size with a larger cup letter, then check that the cup still contains breast tissue comfortably.