Most women wear the wrong bra size — and it’s not their fault. Our free bra size calculator uses real measurement science, sister-size logic, and breast shape matching to find the size that actually fits. Covers US, UK, EU, AU, JP, KR, FR & more — A through P cups, 40+ brands.
“I wore a 34B for years. This calculator showed me I’m actually a 30FF — it changed everything.”
— Mia L., verified user
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Bra Size Chart 2026:
International Converter
Over 80% of women wear the wrong bra size — usually because sizing differs so much between countries and brands. This guide gives you the full picture: accurate conversion tables for US, UK, EU, Japan, Australia, and France, plus the sister-size logic and expert fitting advice that no generic chart tells you.
Conversion tables for 6 major sizing systems used worldwide
Updated sizing data from leading lingerie brands this year
Real advice on shape matching, sister sizes, and fit problems
Instant results with our advanced size calculator
Quick Bra Size Conversion Chart 2026
Find your current size in the US column and read across to see your equivalent in every other system. Remember: cup letters diverge between US, UK, and EU — especially above a D cup.
| US | UK | EU | France | Japan | Australia |
|---|---|---|---|---|---|
| 30B | 30B | 65B | 80B | 65B | 8B |
| 30C | 30C | 65C | 80C | 65C | 8C |
| 32B | 32B | 70B | 85B | 70B | 10B |
| 32C | 32C | 70C | 85C | 70C | 10C |
| 34C | 34C | 75C | 90C | 75C | 12C |
| 34D | 34D | 75D | 90D | 75D | 12D |
| 36DD | 36E | 80E | 95E | 80E | 14DD |
| 36DDD | 36F | 80F | 95F | 80F | 14E |
| 38DDD | 38F | 85F | 100F | 85F | 16E |
| 40G | 40FF | 90G | 105G | 90G | 18F |
| 42H | 42GG | 95H | 110H | 95H | 20G |
How to Measure Your Bra Size Correctly
Two measurements are all you need. Most mistakes happen from measuring over a padded bra, or measuring loosely. Take both measurements on bare skin or a non-padded bralette.
Measure Your Band (Underbust)
Wrap a tape measure snugly directly under your bust, around your ribcage. Keep it parallel to the floor. If you get an odd number, round up to the next even number — that’s your band size.
Measure Your Bust (Fullest Point)
Measure around the fullest part of your bust — usually across the nipples — keeping the tape level. Subtract your band measurement from this number. That difference gives your cup size.
International Band Size Chart
Band numbers look very different across countries — but they all refer to the same underbust measurement. Here’s how to translate your band across every major system.
| US / UK | EU | France | Japan | Australia | Underbust (inches) |
|---|---|---|---|---|---|
| 28 | 60 | 75 | 60 | 6 | 23–24″ |
| 30 | 65 | 80 | 65 | 8 | 25–26″ |
| 32 | 70 | 85 | 70 | 10 | 27–28″ |
| 34 | 75 | 90 | 75 | 12 | 29–30″ |
| 36 | 80 | 95 | 80 | 14 | 31–32″ |
| 38 | 85 | 100 | 85 | 16 | 33–34″ |
| 40 | 90 | 105 | 90 | 18 | 35–36″ |
| 42 | 95 | 110 | 95 | 20 | 37–38″ |
Cup Size Chart — Bust Minus Band
Your cup size is the difference in inches between your bust and your band. The tricky part? The same difference means different letters depending on the country. Here’s the full breakdown.
| Difference (inches) | Difference (cm) | US Cup | UK Cup | EU / Japan / France |
|---|---|---|---|---|
| 1″ | 2.5 cm | A | A | A |
| 2″ | 5 cm | B | B | B |
| 3″ | 7.5 cm | C | C | C |
| 4″ | 10 cm | D | D | D |
| 5″ | 12.5 cm | DD | DD | E |
| 6″ | 15 cm | DDD / F | E | F |
| 7″ | 17.5 cm | G | FF | G |
| 8″ | 20 cm | H | GG | H |
| 9″ | 22.5 cm | I | H | I |
| 10″ | 25 cm | J | HH | J |
Same Cup Volume, Different Band
Sister sizes are bras with the same cup volume but a different band width. If your usual size feels off in the band — too tight or too loose — a sister size gives you the same fit with a more comfortable band. This is one of the most useful fitting tricks most women never learn.
All three hold the same cup volume — only the band width changes
| Your Size | Band Too Tight? Try → | Band Too Loose? Try → |
|---|---|---|
| 32DD | 34D | 30F |
| 34C | 36B | 32D |
| 34D | 36C | 32DD |
| 36D | 38C | 34DD |
| 36DD | 38D | 34DDD |
| 38DD | 40D | 36E (UK) / 36DDD |
| 40G | 42F | 38H |
Regional Sizing Differences Explained
Same body, six different size labels. Here’s what actually differs between each country’s system and how to shop confidently across borders.
Uses inches. Cup letters repeat after D (DD, DDD). The most widely sold system globally, but cup labels often confuse shoppers used to UK or EU sizing.
Band sizes identical to US. Cup letters go E, F, FF, G, GG after DD — not DDD. The UK system is used by many European brands like Panache, Freya, and Fantasie.
Band sizes use centimeters and run larger (EU 75 = US/UK 34). Cup letters align more closely with UK than US. Most French and German brands follow this system.
France adds an extra 15 to the EU band number — a US 34 band becomes France 90. Cup letters follow EU convention. Common in French luxury lingerie brands.
Similar to EU sizing in bands. Cup sizes generally run 1–2 smaller than US/UK equivalents. Japanese A cup ≈ US AA. Always add 1–2 cups when buying Japanese brands.
Band numbering goes 6, 8, 10, 12 (not 28, 30, 32, 34). Cup letters follow UK convention. AU 12C = US/UK 34C. Australian sizing is arguably the easiest to navigate.
How Popular Brands Actually Fit
Even within the same sizing system, brands fit differently. A 34D in Victoria’s Secret won’t feel the same as a 34D in Panache. Here’s what to expect from the brands most women shop — so you don’t have to guess.
Runs small in band, consistent in cups. If you’re between bands, size down. Good for smaller cup sizes (A–DDD).
True to size. Exceptional support for larger cup sizes (D–K). One of the most accurately sized brands in the market.
Generous in cups, softer bands. Great for wide-set or projected shapes. Band may feel looser than expected.
Modern, minimalist fit. Often cuts smaller in cups. Best for smaller busts or those who prefer a compressive feel.
Asian fit standard — runs 1 cup smaller overall. Size up one cup from your usual when trying Wacoal for the first time.
Offers half-cup sizes (e.g., 34C½). Generally true to size. Excellent if you’ve always felt between two cup sizes.
Common Bra Fit Problems — Solved
If something feels off, it almost always points to a sizing issue — not your body. Here’s how to diagnose and fix the most common bra fit problems.
Band is too loose. Go down a band size and up a cup size to keep the same volume. The band should sit level all the way around.
Cup is too small. Size up one cup — don’t size up in band. Spillage is the clearest sign you need a larger cup size.
Can mean cup is too large — but often it’s a shape mismatch. Try a different style (balconette, plunge) before changing cup size.
The band isn’t doing its job. A properly fitted band carries 80% of the support — straps should just guide, not hold everything up.
If wires poke the sides, the cup is too small. If the wire floats off your chest, the cup may be too large or the style wrong for your shape.
Usually means the cup is too small or the style doesn’t suit your breast placement. Try a fuller-cup style or go up one cup size.
Frequently Asked Questions
The questions we get asked most — answered clearly, without jargon.
Are US and UK bra sizes the same?
Why do EU bra band sizes look so much bigger?
Do Japanese bras run smaller?
What are sister sizes and when should I use them?
How often should I measure my bra size?
Why does my bra size change between brands?
What 4 Million+ Women Say
“I wore a 34B for 12 years. This calculator showed me I’m a 30FF. The difference in comfort is life-changing — I had no idea back pain could just disappear.”
“Bought from a UK brand for the first time and used the conversion chart here. Perfect fit, first try. Saved me from making an expensive mistake.”
“The sister size tip was the thing I never knew I needed. I went from a too-tight 34D to a 36C and it fits beautifully. Such a simple fix.”
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