Bra Size Calculator
Measure your underbust and bust to calculate your bra size in US, UK, EU, AU, and FR sizing — with sister sizes and fitting guidance.
- 1.Wear a non-padded bra (or none). Measure over bare skin or a thin, unpadded bra. Padded or sports bras compress tissue and skew results.
- 2.Measure your underbust (band). Wrap the tape directly under your bust, level around your ribcage. Pull snug but not tight — you should be able to breathe normally. Record in cm or inches.
- 3.Measure your bust (fullest point). Wrap the tape around the fullest part of your chest, usually across the nipples. Keep the tape parallel to the floor and without compressing tissue.
- 4.Stand straight and breathe normally. Relax your shoulders, stand in front of a mirror, and measure on the exhale for the most consistent reading.
US Cup Size Chart
Cup size = bust measurement minus band size (in inches). Each inch of difference maps to a cup letter.
| Bust − Band | US Cup |
|---|---|
| Less than 1" | AA |
| 1" | A |
| 2" | B |
| 3" | C |
| 4" | D |
| 5" | DD / E |
| 6" | DDD / F |
| 7" | G |
| 8" | H |
| 9" | I |
| 10" | J |
How to Measure Your Bra Size at Home
Finding the right bra size starts with two measurements: your underbust (band) and your bust (fullest point). Unlike clothing sizes that vary wildly by brand, bra sizing follows a mathematical system — a band number and a cup letter derived from the difference between those two measurements.
For the band, wrap a soft tape measure directly under your bust where the band sits. Pull it snug but not tight — you should breathe normally. For the bust, measure around the fullest part of your chest, keeping the tape level across your back. Most people find it easiest in front of a mirror.
Our calculator uses the modern fitted method: your band size is your underbust rounded to the nearest even inch (e.g., 31" → 32 band). Your cup size is the difference between your bust and that band number. A 36" bust with a 32" band gives a 4-inch difference — a D cup — so your size is 32D.
Signs Your Bra Fits (or Doesn't)
Good Fit
- ✓Band sits level across your back on the loosest hook
- ✓All breast tissue is enclosed in the cups
- ✓Underwire encircles tissue and rests on the ribcage
- ✓You can fit two fingers under the band comfortably
Too Small
- ✗Band rides up in the back
- ✗Breast tissue spills over the cups (quad-boob)
- ✗Underwire digs into breast tissue
- ✗Straps dig in because the band isn't carrying weight
Too Large
- ✗Band gaps away from your back when fastened on the loosest hook
- ✗Cups gape or wrinkle even when scooped and swooped
- ✗Underwire sits on breast tissue instead of the ribcage
- ✗Straps fall off shoulders constantly
International Bra Size Conversion
US & UK share the same band numbers (28, 30, 32, 34…). Cup letters diverge after D — US DDD is UK E, US G is UK F.
EU (EN 13402) uses centimeters for the band (60, 65, 70, 75, 80…) with each 2 cm of bust-to-underbust difference equal to one cup size.
France, Belgium & Spain label the band as underbust + 15 cm — so a 75 cm underbust is a FR 90. Cup letters follow the EU system.
Australia & New Zealand follow UK sizing. A UK 12B roughly corresponds to a US 34B in dress size correlation, but bra band numbers are the same as UK.
India has no separate national bra size standard. Most domestic brands — Zivame, Clovia, Jockey, Enamor, Amante — label bras in US sizing (32B, 34C). Myntra and Nykaa often display both US and EU (75B) on product pages; when in doubt, use the US size shown in this calculator.
This calculator provides an estimated starting size for educational purposes. Bra fit varies by brand, style, and breast shape. For medical concerns, consult a healthcare professional.
About the Bra Size Calculator
Calculates bra band and cup size from underbust and bust measurements using the modern fitted method, with conversions to US, UK, EU, AU, and FR sizing plus sister size recommendations.
Use before buying bras online or when your current size feels wrong. Measure with a soft tape at home and compare international size labels.
An underbust of 75 cm and bust of 90 cm typically yields EU 75C or US/India 32C — but always verify fit by trying bras on.
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