Cup Size Conversion: International Bra Cup Size Guide

Shopping for a bra from a different country can feel like decoding a foreign language. Whether you’re ordering from a UK brand or browsing European sizes online, understanding cup size conversion is essential for finding your perfect fit. This guide breaks down everything you need to know about translating your bra size across international systems.

How to convert cup sizes between countries

Here’s what you need to know right away: cup letters do not match 1:1 between different bra sizing systems. The UK uses double letters like DD, E, F, FF, while the US often jumps from D to DD, DDD, then G. Understanding this difference matters when you shop internationally. To measure your bust size, measure around the fullest part of your breast while standing straight with arms to the side.

For a quick example: US 34D ≈ UK 34D, EU 75D, FR/ES 90D, AU 12D. Another common conversion: US 36DD ≈ UK 36E, EU 80E, FR/ES 95E, AU 14DD.

To go up a band size, you go down one cup letter (e.g., 36C to 38B). A US 34D is often equivalent to a European 75E. Common equivalents for bra sizes include 32DD = 34D = 36C = 38B = 40A. Common equivalents for bra sizes include 32DD = 34D = 36C = 38B = 40A. A 34B has the same volume as a 32C or 36A.

This calculator provides results for the United States, the United Kingdom, the European Union, France, Belgium, Spain, Australia, and New Zealand. Understanding these conversions is crucial for online shopping, international purchases, or simply when you encounter a foreign brand. To find your bra size using the International Conversion Chart, start by knowing your current bra size in the US system. While the International Bra Size Conversion Chart provides a helpful starting point for converting sizes across different countries, it's essential to note that sizes may vary by brand and bra style. Bra size equivalents will always vary from brand to brand, so always check if you're not sure and use this chart as a guide only. Using the bra size chart, you can convert your bra sizes from one country to another.

Note that you must convert the band to the same system before comparing cups. A US 34 corresponds to EU 75, not EU 34. The sections below explain detailed conversion charts, measurement steps, and troubleshooting for tricky sizes.

What is a bra cup size? (explaining band vs. cup)

Every bra size combines two elements: a band number and a cup letter. When you see “34D,” the 34 represents your band size and the D indicates your cup size.

The band measurement wraps around your ribcage just under your bust. US and UK sizing uses inches, while EU, FR, ES, and JP systems use centimeters. This back size provides the primary support for your bra.

The bra cup reflects the difference between your bust measurement and your band measurement. Each inch of difference corresponds to a letter, the larger the difference, the larger the cup, which is why understanding how bra cup letters really work can dramatically improve your fit.

Here’s something many women don’t realize: a 34D and a 38D do not hold the same breast tissue volume. This introduces the concept of sister sizes. For example, 34DD ≈ 36D in volume, just with different band tightness, which also affects whether you perceive a D cup as "big" or not. Different countries apply this same principle but label everything differently, which is why a conversion chart becomes essential.

How to measure for cup size at home (step-by-step)

Measuring yourself takes under five minutes with a soft tape measure and a mirror. You can calculate your size accurately at home before you even step into a store.

For your band measurement, stand straight with your arms relaxed at your sides. Exhale gently to relax your ribcage. Wrap the tape snug around your underbust, keeping it parallel to the floor. Record this number in both inches and centimeters as part of a comprehensive bra size guide.

For your bust size, measure around the fullest part of your bust, typically at nipple level. Keep the tape comfortably loose but flat across your back, not tight. Again, record in inches and centimeters.

To calculate your cup in US/UK sizing, subtract your band from your bust measurement. Each inch of difference equals one cup: 1”=A, 2”=B, 3”=C, 4”=D, 5”=DD/E, 6”=DDD/F, reflecting the basic cup size difference and how bra sizes work.

Worked example: Underbust measures 31 inches (round to 32 band). Bust measures 36 inches. The difference is 4 inches, giving you a 32D. If measurements fall between whole numbers, try both adjacent sizes to determine which feels right.

International cup size conversion basics

Converting between bra sizing systems requires understanding both band and cup variations. A universal 'cup' measurement is not established; a US cup is 240 ml, while many countries use a metric cup of 250 ml. Here’s how US, UK, EU, France/Spain, Japan, and Australia systems differ.

Band numbers shift between systems following specific patterns:

EU sizes typically use single letters (A through K) without duplicates, aligning roughly with UK but simpler. France and Spain combine EU-style cups with band numbers 15 higher than EU, so EU 75D equals FR/ES 90D, and many shoppers find bra size charts with visual examples helpful for keeping these systems straight.

Japanese and Australian systems use their own band numbers but cups generally correspond to EU or UK letters, with minor variation in larger sizes.

Practical cup size conversion examples

Rather than overwhelming you with tables, here are three common conversions spelled out completely:

Example 1 – US 32C: (a size whose sister range includes options like 30D bra size fit and measurements)

• UK 32C, EU 70C, FR/ES 85C, AU 10C, JP 70C
• The 32-inch band converts to 70cm in EU and 85 in FR/ES

Example 2 – US 34DD: (a common point on the spectrum when comparing DD vs DDD cup differences)

• UK 34E, EU 75E, FR/ES 90E, AU 12DD, JP 75E
• Note that US “DD” often equals UK “E” at this size

Example 3 – US 38DDD: which often overlaps with E cup sizing and fit depending on the brand and country system.

• UK 38F, EU 85F, FR/ES 100F, AU 16F, JP 85F
• US “DDD” typically equals UK “F”, a common point of confusion

Some manufacturers label sizes inconsistently, with “E” appearing where others write “DD.” For sizes above G, expert fitters recommend using detailed bra size converter tools, as naming varies significantly between brands.

Common cup size conversion pitfalls and how to avoid them

Studies suggest 70-85% of women wear the wrong bra size, often due to conversion mistakes and brand differences. Knowing what to avoid helps you find a properly fitted bra.

Common mistakes include:

• Assuming all D cups hold the same volume (they don’t, band size matters)
• Ignoring band conversion (treating US 34 as EU 34 instead of EU 75)
• Treating US and UK cups as identical past D

Signs your cup size is wrong:

• Spillage over the top or sides (cup too small)
• Gaping or wrinkling fabric (cup too large)
• Underwire sitting on breast tissue instead of around it
• Center gore floating instead of tacking flat against your body
• Straps digging causing shoulder pain

An incorrect bra band often leads to choosing the wrong cup. A loose band that rides up might make you think you need 38B when 34D would provide proper support, especially once you understand how a 34D size fits different body types.

Troubleshooting steps:

• Try sister sizes (one band down, one cup up)
• Test different brands since patterns vary
• Re-measure if nothing feels right

Remember: conversion charts are starting points. The perfect bra fit comes from how it actually feels when you’re wearing it.

FAQ: Cup size conversion & fit questions

Are US and UK cup sizes the same? Up to D, they’re usually similar. Beyond D, they diverge, UK uses DD, E, F, FF while US often uses DD, DDD, G. Always check a size chart when ordering UK bra size styles.

Can I use one conversion chart for all brands? Charts are approximate because each brand’s patterns and fabrics vary. A Freya 32E might fit differently than a Wacoal 32E. Use charts as guides, then adjust based on fit.

How often should I re-measure my cup size? At least once per year. Also re-measure after weight changes of 10+ pounds, pregnancy, nursing, or significant fitness changes. Your body doesn’t stay static.

What if my converted cup size still doesn’t fit? Try sister sizes first, if 34DD feels wrong, test 32E or 36D. Check both band and cup fit separately, especially if you’re working within D-cup sizing and fit considerations. Prioritize comfort and support over what the label says.

How do sports bras and bralettes use cup sizes? Many use alpha sizing (XS through XL) rather than traditional measurements. For example, 32A-34B often corresponds to XS, while 36C-38D maps to M. Check brand-specific charts on their website to convert your size accurately.