The Shoe Sizing Chaos, Explained (Plus an Interactive Converter That Actually Works)

In our companion article on global foot sizes →, we covered how foot dimensions vary across populations. But knowing your foot is 27cm long doesn't help much when one store labels that a 10, another calls it a 9, and a third says it's a 44.

Shoe sizing is, objectively, one of the most absurd systems in global commerce. Here's why it's such a mess, how each system actually works, and — at the bottom — an interactive converter so you never have to guess again.

Why Every Country Uses a Different System

The short answer: each system was invented independently, at different times, by different industries, using different units. Nobody coordinated, and by the time anyone thought to create a standard, it was too late — the legacy systems were already entrenched.

The Systems, Decoded

US Sizing (Brannock System)

Introduced in 1927 by the Brannock Device Company. Size 0 corresponds to a foot length of 3.94 inches (infant), and each full size adds 1/3 of an inch. Men's and women's sizes are offset by approximately 1.5 sizes — a women's 8 is roughly equivalent to a men's 6.5.

The quirk: US sizing has half sizes, giving reasonably precise fit. But the men's/women's offset means you always need to specify gender when stating a US size.

UK Sizing

Similar in structure to US sizing but starts from a different zero point. UK sizes run roughly 0.5–1 size smaller than US men's and about 2 sizes smaller than US women's.

The quirk: UK men's and UK women's sizing also uses different scales, though many brands are moving toward unisex UK sizing. Always check the brand's chart.

EU Sizing (Paris Points)

Based on a unit called the Paris Point, which equals 2/3 of a centimeter (about 6.67mm). EU sizing is unisex — the same scale for men and women — which is simpler in one way but means you can't infer gender from the number.

The quirk: EU sizes don't always include half sizes (some brands do, some don't), which can make the jumps between sizes feel larger than in US/UK systems.

Japanese Sizing (cm)

The most logical system: it's simply the foot length in centimeters. A 27cm foot wears a size 27. Straightforward, metric, and elegant. Used in Japan and increasingly referenced by international brands.

The quirk: It's almost too simple — some people don't believe it's actually just centimeters.

Chinese/Korean Sizing (mm)

China and Korea both use millimeter-based systems. A 270mm foot wears a 270. Like the Japanese system, it's based directly on foot measurement and is inherently more accurate than arbitrary scales.

The quirk: Older Chinese sizing used a different system (Paris Points plus 10), so vintage or traditional Chinese shoes may use confusing numbers. Modern brands have largely standardized on the mm system.

Australian Sizing

For men, Australian sizing is nearly identical to UK sizing (sometimes offset by half a size). For women, it's closer to US sizing. This makes it one of the more confusing systems because it's almost the same as two other systems but not quite.

The quirk: The inconsistency between men's and women's references means Australians frequently deal with the same conversion headaches as everyone else.

The International Standard Nobody Uses

ISO 9407 (the Mondopoint system) defines shoe size by foot length and width in millimeters. It's rational, precise, and universally applicable. Military and some industrial footwear uses it. Consumer footwear almost universally ignores it.

The reason: switching systems would require every brand to relabel, every consumer to relearn, and every retail environment to restructure. The cost of coordination exceeds the cost of confusion — so the confusion persists.

Tips for Shopping Across Systems

Measure your foot in centimeters. This is the universal anchor. Once you know your foot length in cm, you can convert to any system reliably. Stand on a piece of paper, mark the heel and longest toe, and measure the distance.

Don't assume your size translates 1:1 between brands. Even within the same sizing system, a Nike 10 and an Adidas 10 can fit differently. Always check the brand's specific size chart.

Width matters as much as length. If a shoe feels tight but the length is right, try a wider version. Many brands offer width options (D, EE, 4E in US sizing) that can make a dramatic difference.

The Japanese and Korean systems are the most reliable for online shopping across borders, since they're based on actual measurement rather than arbitrary scales.

Use Our Interactive Converter

Done guessing. Select your gender, your known sizing system, and your size — the converter returns your equivalent across US, UK, EU, JPN, CHN/KOR, and AUS instantly. The full reference chart is below it for browsing.

[Interactive Shoe Size Converter — embedded below]

Shoe sizes vary between brands and models. These conversions are approximate industry standards. For the most accurate fit, measure your foot length in cm and consult brand-specific charts.