Bra Size Chart — US, UK, EU & International Conversions
Navigating bra sizing across different brands and countries can be confusing. Every bra size consists of a band number (the ribcage measurement) and a cup letter (the volume difference between bust and underbust). Use this reference chart to compare sizes across verified international sizing systems.
International Size Conversion Matrices
Search or filter below to highlight equivalent band and cup sizes across regions.
Band Size Conversion MatrixUS / UK / EU / FR / AU / JP
| US / CA | UK | EU | FR / BE / ES | AU / NZ | JP |
|---|---|---|---|---|---|
| 30 | 30 | 65 | 80 | 8 | 65 |
| 32 | 32 | 70 | 85 | 10 | 70 |
| 34 | 34 | 75 | 90 | 12 | 75 |
| 36 | 36 | 80 | 95 | 14 | 80 |
| 38 | 38 | 85 | 100 | 16 | 85 |
| 40 | 40 | 90 | 105 | 18 | 90 |
Cup Size Conversion MatrixUS / UK / EU / AU / JP
| US / CA | UK | EU | AU / NZ | JP |
|---|---|---|---|---|
| A | A | A | A | A |
| B | B | B | B | B |
| C | C | C | C | C |
| D | D | D | D | D |
| DD / E | DD | E | DD | E |
| DDD / F | E | F | E | F |
| G | F | G | F | G |
| H | FF | H | FF | H |
| I | G | I | G | I |
| J | GG | J | GG | J |
How to Read a Bra Size
A standard bra size consists of two parts: the Band Size (a number such as 34 or 75) and the Cup Size (a letter such as C, D, or DD).
1. Band Size (Number)
Represents your snug ribcage measurement directly beneath your bust. In US/UK sizing, bands run in even numbers (30, 32, 34, 36). In EU sizing, bands are measured in centimeters (65, 70, 75, 80).
2. Cup Size (Letter)
Represents the volume difference between your full bust measurement and your underbust band measurement. Each letter step generally corresponds to 1 inch (or 2.5 cm) of bust volume difference.
💡 Key Concept: Cup letters do not represent fixed volumes on their own. A 32D cup holds less volume than a 38D cup. Cup letter size is always relative to band size.
Understanding Sister Sizes
Sister sizes are bra sizes that hold the exact same cup volume capacity despite having different band measurements. When you go up one band size and down one cup letter (or vice versa), the physical volume inside the cup remains identical.
Sister Size Example for 34C:
- 32D (Smaller Band, Larger Cup Letter → Tight Band, Same Volume)
- 34C (Your Baseline Starting Size)
- 36B (Larger Band, Smaller Cup Letter → Loose Band, Same Volume)
To calculate your exact baseline size and see your 3-card sister size breakdown automatically, use our free Bra Size Calculator.
How to Find Your Recommended Bra Size
Establishing your baseline bra size takes less than two minutes using a soft measuring tape:
- Measure your underbust snugly around your ribcage directly beneath your bust.
- Measure your bust loosely around the fullest part of your chest.
- Enter your measurements into our Bra Size Calculator.
- Review our step-by-step How to Measure Guide for measuring tips.
Important Fit Note
Your calculated bra size is a recommended starting point. Because sizing conventions, band elasticity, cup cuts, and wire shapes vary between manufacturers and styles, you may find that your best-fitting size shifts slightly between different brands. Use our Fit Guide to diagnose common fit issues such as band riding up, gaping cups, or digging wires.