Fit & Measurement
How to Measure Your Bra Size Correctly
2 min read · Updated July 3, 2026
The 'add four inches to your under-bust' method taught to a generation of shoppers is wrong. Modern fitters use direct measurements — snug, in your best-fitting bra — and pick the closest chart entry.
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You need two numbers
- Under-bust: soft tape directly under the bust, snug enough that it doesn't slip, level all the way around.
- Bust: same tape at the fullest point of the bust, standing straight, wearing a non-padded bra.
Band size = under-bust, rounded
For US/UK, round the under-bust in inches to the nearest even number: 30.5 → 30, 31.5 → 32. For EU, use the cm measurement rounded to the nearest 5: 76 cm → 75, 78 cm → 80.
Cup size = bust minus under-bust
| Difference (in) | US Cup | UK Cup | EU Cup |
|---|---|---|---|
| 1 | A | A | A |
| 2 | B | B | B |
| 3 | C | C | C |
| 4 | D | D | D |
| 5 | DD | DD | E |
| 6 | DDD/E | E | F |
| 7 | F | F | G |
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The fit checks
- The band should sit level, parallel to the floor, not ride up in the back.
- You should fit two fingers under the band, no more.
- Underwire should sit flat against the ribcage, not on breast tissue.
- Cups should contain the entire breast without spillage or gapping.
Calculator
Bra fit calculator
Enter under-bust and bust; get your size across all systems.
Frequently asked questions
- Should I measure with or without a bra?
- With a non-padded bra that fits reasonably well. Bare-measurement understates cup size for larger cups.
- Why does my size change between brands?
- Cup volume varies. A 32DD at one brand can be a 32E at another using UK sizing. Use the brand's own chart.
Keep reading
Calculators
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Reviewed by the SizeAtlas editorial team · Last updated July 3, 2026