Already know your size in one system and just need the equivalent elsewhere? This is the fastest way there.
Accurate, private, and always free- no signup, and nothing you enter is stored.
How It Works
Pick your current sizing system, enter your band and cup, and the converter reverse-calculates your underlying measurement to show every other system at once. US, UK, Europe, Italy, Australia, Japan, and South Korea.
When to Use This vs. The Main Calculator
Use this converter when you already trust a known size and just need it translated. Use the Main Bra Calculator instead if you’re measuring fresh or unsure your current size is actually correct.
Country-Specific Calculators
Prefer a calculator already set to a specific country? Browse our Full country list.
Why Seven Different Systems Exist
Band measurement units differ (inches vs. centimeters), and each region’s cup-letter ladder shifted independently over decades of local retail history. That’s why the same physical size gets a different label depending on where you’re shopping.
The Mistake Most Converters Make
A flat rule like “add two sizes for UK to US” only works for a narrow part of the range and breaks down at the extremes, because band and cup shift by different amounts across different systems. This converter recalculates from your actual underbust measurement every time instead of applying a single flat offset.
Shopping From Another Country
When ordering from an international retailer, convert your size before you shop rather than guessing from the number alone, and check whether the site lists sizes in the local system or has already converted for you, since double-converting is a common and avoidable mistake.
When Converted Sizes Still Feel Off
A correct conversion still assumes a similar cut and construction. Brand-specific variation (see the Brand Size Decoder) sits on top of the system conversion, not instead of it.
A Worked Example
Say your US size is 34C. Converting: the band stays 34 inches for UK, becomes roughly 77cm for EU/France (34 × 2.54 + 16, rounded to the nearest 5), and about 86cm for Japan and Korea (underbust alone, rounded to the nearest 5, without the +16 padding EU uses).
The cup letter shifts too. A US C becomes a UK C, but an EU C sits one step differently than IT and JP equivalents because each system’s cup ladder is labeled slightly differently past a certain point.
A Common International Shopping Mistake
Assuming every country’s system shifts by the same fixed offset is the most common error. It doesn’t.
Some systems only change the band’s unit (inches to cm) while keeping cup letters aligned; others also shift the cup ladder itself. That’s exactly why a dedicated converter is more reliable than a simple “subtract 2” or “add one letter” rule of thumb passed around informally.
A Worked Multi-Country Example
A US 34D converts to a UK 34D (same numbers, different cup letter convention coincidentally aligning here), a EU 75E (band in cm, cup shifted), an Italian 80F, and a Japan/Korea 75E. Five different-looking labels describing the exact same physical size. This is why converting by number pattern-matching alone, without the actual formula, leads to mistakes.
Why Some Countries Aren’t a Simple Formula
Countries outside the systems with well-documented standard formulas (like several Asian, Middle Eastern, and Latin American markets) often size based on whichever import brand’s convention is most common locally, rather than one unified national standard, which is why this tool flags some countries as “depends on the brand’s origin” rather than giving a false precise conversion.
Why a Single Physical Measurement Drives Every System
This converter works backward from one real measurement (your underbust in centimeters) rather than treating each country’s sizing system as a separate lookup. That’s what keeps all seven systems mathematically consistent with each other instead of relying on seven different conversion charts that could disagree.
Saving Your Result for Future Reference
Since this tool doesn’t store anything, jotting down your band and cup in centimeters somewhere you’ll remember makes future international shopping faster without needing to re-measure each time.