Bra Size Calculators by Country

The US system causes the most global confusion because it uses doubled cup letters — DD, DDD, DDDD — beyond D cup, while most other countries use unique single letters (E, F, G). A US DDD is equivalent to an Australian or UK E, an EU F, and a Japanese F. This four-label discrepancy for a single cup volume is the root cause of most international sizing errors, particularly when Australian or British shoppers buy from American retailers like Victoria’s Secret or ThirdLove.

The cup letter is identical — both the UK and Australia use the same extended cup alphabet (A, B, C, D, DD, E, F, FF, G, GG, H, HH). The band number is different. A UK 36C uses the inch-based band 36. An Australian 12C uses the dress-size band 12, which corresponds to the same underbust measurement. Both describe an underbust of 73–77 cm. So an AU 12C equals a UK 36C — same body, different band label.

French bra sizing uses the same cup letters as the EU system but adds 15 to every band number. An EU 75B becomes a French 90B. An EU 80C becomes FR 95C. This offset exists because France historically used a different base measurement convention. Brands like Chantelle, Aubade, and Simone Pérèle use French sizing on their labels, while brands manufactured for broader European markets typically use the standard EU number.

No. Japan uses a single-letter cup system that runs from AAA through H, with no doubled letters (no DD, DDD, or FF notation). A Japanese E cup is equivalent to a UK E or US DDD. Japanese band numbers look similar to EU bands — 70, 75, 80 — but the cup intervals are measured in 2.5 cm increments from a slightly different starting point. Wacoal and Triumph Japan are the two brands most Australians and Europeans encounter when buying Japanese bras.

Use the calculator for the country where the brand is based — not where you live. If you’re in India buying from ASOS (UK-based), use the UK calculator. If you’re in Australia buying from Victoria’s Secret (US-based), use the US calculator, then convert the result back to a size you recognise. Each brand sizes according to its own country’s convention, and using the wrong country’s calculator is the most common source of online sizing errors.

Sister sizes are bra sizes with an identical cup volume but different band widths. Going up one band and down one cup letter — for example, from AU 12C to AU 14B — gives you the same breast volume in a looser band. Sister sizes exist in every sizing system and work identically regardless of country. An AU 12C, UK 36C, and EU 80C are all in the same sister size family and share the same cup volume. Our country calculators display both sister sizes automatically in your country’s native labelling.

A well-built calculator that uses your actual underbust and overbust measurements in centimetres or inches is accurate within one sister size for approximately 85% of women. Accuracy improves when you measure without a padded bra, keep the tape horizontal, and remeasure both underbust and overbust at the same time. The remaining 15% of cases involve unusual proportions — very shallow breast roots, significant asymmetry, or post-surgical anatomy — where an in-person fitting with a specialist like Bravissimo (UK) or Bras N Things (AU) provides a more refined result.

Every brand uses its own block (pattern template) to construct cups and bands, even when the size label is identical. In Australia, a Berlei 12C follows a strict 2.5 cm cup grading; a Bonds 12C uses approximately 2 cm per cup letter, making the cups slightly smaller. Victoria’s Secret bands tend to run small and cups generous compared to their US label equivalent. The only reliable approach is to know your true measurement, understand the conversion to the brand’s system, and then use brand-specific fit reviews to calibrate within that system.

Remeasure every six months at minimum, or whenever you experience weight change of 3 kg or more, pregnancy, breastfeeding, hormonal changes, or noticeable changes in how your current bras fit. Rib cage circumference and breast tissue density both shift significantly with these events. Most women who have worn the same bra size for more than two years without measuring are wearing an incorrect size. A fresh two-minute measurement and recalculation can reveal a size change of one or even two band or cup sizes.

The most commonly purchased bra size varies significantly by country. In the US and Australia, 36C and 34C are consistently the most sold sizes. In the UK, 36D and 34D represent a larger share of sales due to broader adoption of D+ sizing. In Japan, 75B and 70B are reported as the most common by Wacoal’s internal sales data. These figures reflect purchasing patterns at mass-market retailers and likely underrepresent larger cup sizes, since many D+ cup wearers buy from specialist retailers not captured in mainstream sales data.

No. There is no single universal bra sizing standard. The International Organization for Standardization (ISO) published ISO 13982 as a framework, but individual countries and brands continue to use their own systems. The closest approach to a global reference is the underbust and overbust measurement in centimetres — these numbers are universal and can be input into any country’s calculator to produce the correct local size. This is why all our country calculators use centimetre or inch raw measurements as inputs rather than asking you to enter an existing bra size label.

Specialist retailers stock considerably larger sizes than high-street chains. In the UK, brands like Bravissimo and Fantasie stock up to a K or L cup (UK labelling) with bands from 28. In Australia, Brava stocks bands to AU 26 and cups through K. In the US, brands like Glamorise and Elomi extend to 54 band and N cup. Japanese brands like Wacoal JP stock to H cup in JP sizing, equivalent to an AU/UK FF cup. For very large sizes, using a country’s specialist retailer and calculator together gives the most accurate result, as standard size charts typically stop at G or H cup.