How to convert bra sizes
Bra band size conversion chart
Bands from 65 to 105 cm with their EU, UK/US and JP equivalents. The cup letter is applied on top of the band; cup scales differ between systems.
| Underbust (cm) | EU | UK / US | JP |
|---|---|---|---|
| 65 | 65 | 30 | 75 |
| 70 | 70 | 32 | 80 |
| 75 | 75 | 34 | 85 |
| 80 | 80 | 36 | 90 |
| 85 | 85 | 38 | 95 |
| 90 | 90 | 40 | 100 |
| 95 | 95 | 42 | 105 |
| 100 | 100 | 44 | 110 |
| 105 | 105 | 46 | 115 |
Bra fitting varies with brand, style and even fabric stretch. The underbust measurement gives a consistent band size, but a professional fitting is the most reliable check.
Why bra sizes look different across countries
A bra size is a band plus a cup, and each country numbers them in its own way. The EU band is the underbust in centimetres, the UK and US bands count inches (so they share numbers), and JP bands add 10 cm to the underbust. On top of that, cup scales diverge after DD. This tool keeps the two dimensions aligned for you.
How to use this bra size converter
Type your underbust measurement in centimetres, or choose a band system and enter the band number directly, then pick your cup letter. The result shows the equivalent EU, UK/US and JP labels, and the chart lets you compare bands row by row.
How to measure underbust and cup correctly
For the band, wrap the tape snugly around your ribcage, just under the bust, and read it in centimetres while breathing out. For the cup, measure around the fullest part of the bust; the difference between the two tells you the cup depth you need.
Tips for a consistent bra fit
Brands cut differently, so always re-check with a style you already own. Remember that sister sizes exist: going down a band and up a cup keeps the same overall volume, which is useful when a band feels tight or loose.
Frequently asked questions
How do I find my band size from my underbust?
Your underbust in centimetres is essentially your EU band — 75 cm underbust points to a 75 band. For UK/US bands, subtract roughly 10 cm and convert the result to inches (for example ~65 cm → 30). The chart does this for every band.
Why do UK and US cups use different letters after DD?
The UK scale continues DDD → E → F while the US scale uses DDD, G, H and so on, which is why the same physical cup is labelled E in the UK and DDD in the US. The converter applies the correct cup letter for each system.
Is JP bra sizing the same as EU?
Not quite. JP bands are usually the underbust plus 10 cm (so an EU 75 band is often a JP 85), while the cup letters track the underbust–bust difference. Expect JP sizing to be available mainly on Japanese and some Asian-market brands.
How reliable are online bra size conversions?
They are a good starting point but not a guarantee: the same letters can fit differently by brand, and padded versus unpadded styles change how a size behaves. Use the underbust-based result as your baseline and adjust by feel.
What is a sister size and when should I use it?
A sister size keeps the cup volume while shifting the band — for example 75D, 80C and 85B are sisters. If a band digs in, try the larger band with a smaller cup instead of just going up a band.