Subscribe
Subscribe
Find your perfect bra size for DIY bralette making, sewing lingerie patterns, and alterations. Get results for US, UK, EU, FR/BE/ES, AU, and NZ sizing — all from two measurements.
Enter your bust and band measurements,
then click Calculate to see your size.
Convert your bra size between international sizing systems
International band size equivalents — note some variation by manufacturer is possible
💡 DIY Sewing Tip: When cutting a bra pattern, use your band measurement (underbust circumference) plus your cup calculation to select the correct pattern size. Always compare to the pattern's finished measurements, not just the size label.
| Band Size | FR / BE / ES | EU (EN 13402) | US & UK (inches) | AU / NZ |
|---|---|---|---|---|
| XXS | 75 | 60 | 28 | 6 |
| XS | 80 | 65 | 30 | 8 |
| S | 85 | 70 | 32 | 10 |
| M | 90 | 75 | 34 | 12 |
| L | 95 | 80 | 36 | 14 |
| XL | 100 | 85 | 38 | 16 |
| XXL | 105 | 90 | 40 | 18 |
| 3XL | 110 | 95 | 42 | 20 |
| 4XL | 115 | 100 | 44 | 22 |
| 5XL | 120 | 105 | 46 | 24 |
Cup size is determined by the difference between bust measurement and band measurement
| Bust–Band diff (inches) | US Cup | UK / AU Cup |
|---|---|---|
| < 1 | AA | AA |
| 1 | A | A |
| 2 | B | B |
| 3 | C | C |
| 4 | D | D |
| 5 | E or DD | DD |
| 6 | F or DDD | E |
| 7 | G or DDDD | F |
| 8 | H | FF |
| 9 | I | G |
| 10 | J | GG |
| 11 | K | H |
| 12 | L | HH |
| 13 | M | J |
| 14 | N | JJ |
| Bust–Band diff (cm) | Continental Europe Cup |
|---|---|
| 10–11 | AA |
| 12–13 | A |
| 14–15 | B |
| 16–17 | C |
| 18–19 | D |
| 20–21 | E |
| 22–23 | F |
| 24–25 | G |
| 26–27 | H |
| 28–29 | I |
| 30–31 | J |
| 32–33 | K |
Why bra fit matters — and how to spot problems
⚠ Incorrect Bra Fit: Surveys suggest that 70–85% of women wear incorrectly fitted bras. The most common mistake is choosing too large a band and too small a cup. Studies also confirm there is no universal standardisation — a 34B from two different brands may fit completely differently, which is exactly why making your own gives you full control.
Commercial bra sizing lacks standardisation — sizes vary by country, brand, and even product line. Making your own bra or bralette from a sewing pattern lets you adjust every measurement precisely: the band elastic, cup depth, wire length, and strap placement.
Use this calculator to find your starting size, then adjust based on a toile (test garment) before cutting your final fabric. A well-fitted DIY bra is often far more comfortable than a store-bought one.
The band (or frame) size is the firm underbust circumference, measured directly beneath the breasts. US and UK sizes are expressed in even-number inches. EU sizes are in centimeters. FR/BE/ES sizes add 15 to the EU value.
When sewing, remember that finished garment measurements include ease — pattern band measurements are typically smaller than your actual underbust to create the necessary stretch fit.
The cup size is determined by the difference between the bust measurement (over the fullest part) and the band measurement (underneath). Every additional inch or 2 cm typically moves up one cup size, though this varies by sizing system.
For sewing patterns, you may need to adjust cup depth, wire length, and cradle width separately — especially for sizes outside the typical AA–D range commonly used in commercial patterns.