Shoe Size Converter

Using the Shoe Size Converter

1. Pick gender - Men, Women or Unisex. Sizes diverge by about 1.5 US numbers between men and women, so this choice matters.
2. Pick your known system - US, UK, EU or JP (Mondopoint, in centimeters).
3. Select your size from the dropdown. The picker shows half sizes where the system allows them.
4. Read every system at once. The component keeps a single internal "foot length in mm" value and maps it back out to all four systems simultaneously.
5. Scroll the chart below the selector for a full reference range.

What the Tool Is Doing

Every size system maps in a messy way to foot length, which is the true physical variable. The EU (Paris point) system uses length_mm = size * (2/3) * 10, counting in 6.67 mm steps. The UK and US systems use the Barleycorn, a 1/3 inch step inherited from medieval English cobbling, so adjacent whole sizes differ by 8.467 mm. JP / Mondopoint is the only honest one - the size number literally equals foot length in centimeters, as specified in ISO 9407:2019. The converter normalizes whatever you enter to foot length in millimeters, then reports the nearest equivalent in each other system. Because US men, US women and UK sizes run on different offset zero-points, half-size increments do not align cleanly - a US men\'s 10 is a UK 9 but not a UK 9.5. The Preact component precomputes a table so lookup is constant-time.

When You Will Use This

• Shopping on an international site (ASOS, Zalando, Uniqlo Japan) that shows only its own system.
• Buying used sneakers on Depop or Grailed where the listing uses a different country\'s size.
• Ordering ski boots or cycling shoes, which often ship in EU sizing regardless of country.
• Translating a running-shoe review quoting foot length in millimeters into your country\'s size.
• Gifting shoes to a traveler whose local size system differs from yours.
• Comparing two brands that run different widths but quote the same country\'s number.

Pitfalls - Sizing Is Not a Clean Conversion

Two physical variables matter: foot length (heel to longest toe) and foot width (ball circumference). Size-system charts capture length only, and most conversions silently assume a single width. Brands vary by 10-15 mm in actual last length between nominally identical sizes; Nike in Vietnam and adidas in Indonesia use slightly different lasts. Half-size rounding is another issue: US half-sizes map to UK sizes that are not quite half between UK whole sizes, so a "US 8.5" in men\'s can map to UK 7.5 in one chart and UK 8 in another. European "French" versus "Paris" point differs by about 2 mm per size step. JP Mondopoint sizing is usually given in 5 mm increments (26.0, 26.5, 27.0 cm) but some athletic brands use 10 mm steps. This tool uses widely recognized industry charts; always consult the brand\'s own fit guide for precision.

A Short History of Shoe Sizing

English cobbling in the 1300s measured shoes in barleycorns - three grains of barley end-to-end, roughly 8.47 mm. Whole UK child sizes started at 4 inches (about a 4-year-old\'s foot) and added one barleycorn per size. UK adult sizes continue that scale from UK size 13 (the biggest child size) upward. The US system split off in the 19th century with a half-size offset for women and different zero-points for men. France developed the Paris point (2/3 cm) which Europe adopted as its standard by the 20th century. Mondopoint, codified in ISO 9407 in 1991 (revised 2019), measures foot length in millimeters directly and is used by military procurement, ski boots and some athletic brands because it is the only length-accurate system. Nothing in footwear is truly standardized; ISO 9407 exists but brand lasts dominate real fit.

Alternatives

Foot tracing at home - stand on paper, trace, measure heel to longest toe in millimeters - and matching against a brand\'s own printed size chart beats any generic converter. Brannock devices (the metal foot-measuring tool in shoe stores) measure length and width simultaneously and have remained the retail gold standard since 1927. Online foot-scan apps (Shoefitr, Volumental) use phone-camera photogrammetry to produce a 3D foot model that maps directly to a brand\'s last library. This converter is fine for a starting guess but should not substitute for measuring your foot and reading the brand-specific fit notes.