Find your bra size in UK, US, and EU sizing from two measurements: underbust and bust. Enter in cm or inches and get your size instantly.
How to Measure
You need two measurements taken with a soft measuring tape:
Underbust — wrap the tape snugly around your ribcage directly below your breasts. It should be level, firm, and parallel to the floor. Do not hold your breath.
Bust — measure around the fullest part of your bust, tape parallel to the floor. It should be snug but not tight enough to compress the breast tissue.
Both measurements should be taken in the same unit. Use the cm / in toggle in the calculator to switch.
How Bra Size Is Calculated
Your bra size has two parts:
Band size (the number): determined by your underbust measurement. UK and US sizes are in inches; EU sizes are in centimeters.
Cup size (the letter): determined by the difference between your bust and underbust measurements. The greater the difference, the larger the cup.
Bra Size Charts
Band Size
| Underbust (cm) | UK / US band | EU band |
|---|
| 63–67 | 28 | 65 |
| 68–72 | 30 | 70 |
| 73–77 | 32 | 75 |
| 78–82 | 34 | 80 |
| 83–87 | 36 | 85 |
| 88–92 | 38 | 90 |
| 93–97 | 40 | 95 |
| 98–102 | 42 | 100 |
| 103–107 | 44 | 105 |
Cup Size
| Difference (cm) | UK cup | US cup | EU cup |
|---|
| < 10 | AA | AA | AA |
| 10–11 | A | A | A |
| 12–13 | B | B | B |
| 14–15 | C | C | C |
| 16–17 | D | D | D |
| 18–19 | DD | DD | E |
| 20–21 | E | DDD | F |
| 22–23 | F | DDDD | G |
| 24–25 | FF | G | H |
| 26–27 | G | H | I |
| 28–29 | GG | I | J |
| 30–31 | H | J | K |
Sister Sizes
If your calculated size doesn’t feel right, try a sister size — a size with the same cup volume but a different band:
- Go up one band size and down one cup size for a looser band: e.g. 34C → 36B
- Go down one band size and up one cup size for a firmer band: e.g. 34C → 32D
The cup volume stays the same; only the fit changes.
Frequently Asked Questions
How do I measure my underbust?
Wrap a soft measuring tape snugly around your ribcage, directly below your breasts. The tape should be level and firm — not loose. Breathe normally and do not pull your stomach in.
How do I measure my bust for bra sizing?
Measure around the fullest part of your bust, keeping the tape parallel to the floor. The tape should be snug but not compressing. Measure over a non-padded bra or a fitted top for the most accurate result.
What does the band size mean?
The band size (the number in your bra size, e.g. 34 or 75) corresponds to the circumference of your ribcage below the bust. UK and US bands are measured in inches; EU bands are measured in centimeters.
What does the cup size mean?
The cup size (the letter in your bra size, e.g. B, C, D) represents the difference between your bust and underbust measurements. A larger difference corresponds to a larger cup. Different systems use different letter sequences — for example, UK size DD equals EU size E.
Why does the UK cup size differ from the US cup size?
UK and US bra sizing share the same band numbers but diverge in cup notation from DD onward. UK uses DD, E, F, FF, G, GG, H... while US uses DD, DDD, DDDD, G, H... The fit is equivalent; only the label differs.
What is the EU bra sizing system?
The EU system uses centimeters for the band size and a slightly different letter sequence for cups. For example, UK 34 DD = EU 75 E. EU sizing is standard across most of continental Europe.
My result doesn't feel right — what should I do?
Bra size calculators give a starting point, not a final answer. If the band feels too tight or the cups gape, try sister sizes: a sister size keeps the cup volume the same while changing the band. For example, 34C and 32D have the same cup volume but different band fits.
