Find your true bra size in under a minute
Measure once, get sizes across Australia, New Zealand, the USA, the UK, Canada, Europe, and more - all from the same two numbers.
Wrap the tape snugly around your ribcage, directly under your bust.
Wrap the tape around the fullest part of your bust.
Your size
How to measure yourself correctly
Use a soft measuring tape, not a rigid one, and measure over a thin, unpadded bra or bare skin. Keep the tape snug but not tight - you should be able to fit one finger underneath. Measure your band while breathing normally, and your bust at its fullest point, usually right across the nipple line.
The number this calculator gives you is a starting point, not a final verdict. Two brands can label the same body two different ways, so once you have your result, it helps to know how to tell if a bra actually fits once it's on. If your measurement lands right between two sizes, or the band and cup feel off in opposite directions, our guide to calculating band and bust size walks through the adjustments in more detail.
How do band and bust numbers become a bra size?
Your band size comes from your underbust measurement, and your cup size comes from the difference between your bust and band - as that difference grows, you move up the cup ladder in fairly regular steps, close to the traditional one inch per cup rule. The table below shows how that same body measurement is labelled across the regions this calculator covers, since a US/UK 34 band is not written as "34" everywhere.
| US / UK / Canada (in) | EU / France* (cm) | Australia / NZ (dress-scale) |
|---|---|---|
| 26 | 55 | 4 |
| 28 | 60 | 6 |
| 30 | 65 | 8 |
| 32 | 70 | 10 |
| 34 | 75 | 12 |
| 36 | 80 | 14 |
| 38 | 85 | 16 |
| 40 | 90 | 18 |
*French and Belgian brands typically add 15 to the EU band number. The cup letter itself is shared across the USA, UK/Canada, EU, and Australia/NZ results on this calculator, only the band number changes by region - see the FAQ below for more on that, or the full country-by-country conversion guide for how individual brands can still differ.
Frequently asked questions
How do I measure my band size?
Wrap a soft tape measure snugly around your ribcage, directly under your bust, keeping the tape level and parallel to the floor. Read the measurement in a normal breath, not while flexing your chest out.
How do I measure my bust size?
Wrap the tape around the fullest part of your bust, usually across the nipple line, keeping the tape level around your back. Wear a non-padded bra or measure without one for the most accurate reading.
What if my measurement falls between two sizes?
Sister-size up: try the next cup letter with the next band size down (for example, if 34C feels tight in the band, 32D uses the same cup volume with a snugger band). Fit varies by brand, so treat the calculator's result as your starting point for trying styles on.
Does this calculator show different cup letters for the USA and UK/Canada?
No, this calculator gives you the same cup letter for both, since USA and UK/Canada results are built from the same measurement logic here, only the band number changes. Real-world brands can still label things differently once you're above a D cup, so if a specific UK or US brand uses its own convention, check that brand's chart too.
Do I need to convert my size when I shop from a European or Australian brand?
Usually, yes. European bands are labelled in centimetres rather than inches, and Australian bands follow a numeric dress-style scale, so a US 34 doesn't show up as '34' on either chart. The band-and-bust table below shows how the same body maps across regions, but it's still worth checking the brand's own chart before buying.