Shoe Size Conversion,
US · UK · EU · CM.

Complete guide

How shoe sizes work around the world

Buying shoes online or abroad is frustrating precisely because every major market has its own sizing convention and none of them convert cleanly to another. A US men's size 10 becomes a UK 9.5, an EU 44, and a 27.3 cm foot length, yet the same number can mean something different for women or children. This guide explains every system so you can shop with confidence.

The five major shoe size systems

US sizing

American shoe sizes are based on the Brannock Device, invented in 1927 by Charles Brannock. Sizes run in ⅓-inch increments, starting from a "zero" point corresponding to an 8.25-inch last (the mould the shoe is built on). Each full size adds ⅓ inch; each half size adds ⅙ inch. Men's and women's sizes use the same scale but are offset by about 1.5 sizes — a women's 8 is roughly equivalent to a men's 6.5 in foot length.

Children's sizes branch into Infant (C) and Youth (Y) categories. Infant sizes count up from 0C (newborn) through 13C, then restart at 1Y and count up to about 7Y, at which point kids typically transition into adult sizes.

UK sizing

British sizing also uses ⅓-inch increments but starts from a different "zero," one size smaller than the US system. As a result, a UK size is generally 1–2 sizes smaller than its US equivalent for men (US 10 = UK 9.5) and about 2 sizes smaller for women (US 8 = UK 6). UK children's sizes follow a unified scale through size 13, then transition into adult European sizing.

EU (European) sizing: the Paris Point system

European sizes use the Paris Point system, where one Paris Point = ⅔ of a centimetre (approximately 6.67 mm). The size number represents the length of the last in Paris Points. Because Paris Points are 6.67 mm and US increments are ~8.47 mm (⅓ inch), US half-sizes don't land on whole EU numbers, hence the common "40-41" ranges you see in conversion charts.

EU sizing is gender-neutral in theory: the same EU number corresponds to the same foot length regardless of whether the shoe is labelled men's or women's. In practice, shoe companies add width and last differences, but the size numbers themselves are unisex.

CM (centimetre) sizing

Used primarily in Japan and South Korea, centimetre sizing directly measures foot length in centimetres, usually rounded to the nearest 0.5 cm. It's the most intuitive system; you measure your foot, look up the number, and you're done. No opaque scale to memorise. A 27 cm foot is a 27 cm shoe. Japanese sizing is otherwise equivalent to CM sizing; some brands also include a width code (A, B, C, D, E, EE, EEE) appended to the size.

Inches sizing

Less common as a retail system, inches refer to raw foot length in inches. It's useful as an intermediate step: measure your foot with a ruler, note the inches, and use a conversion chart. The Brannock Device reads both inches and US sizes simultaneously; that's how the US system was calibrated in the first place.

How to measure your foot accurately

Shoe sizing starts with a reliable foot measurement. Follow these steps for the most accurate result:

1. Time it right: Measure in the late afternoon or evening. Feet swell throughout the day from activity and gravity — they can be up to a full size larger by dinner than at breakfast. Always buy shoes for your largest measurement.
2. Wear your usual socks: If you'll wear the shoes with thick hiking socks, measure with those on. Thin dress socks give a different baseline.
3. Trace both feet: Most people have a dominant foot that's 3–7 mm longer. Stand on a piece of paper, place a pen vertically against your heel and longest toe (usually the big toe or second toe), and mark both points.
4. Measure heel to toe: Use a ruler or tape measure to find the distance in centimetres between your two marks. Round up to the nearest millimetre.
5. Add 1–1.5 cm: Shoes should have a thumb's-width of space (about 1–1.5 cm / ½ inch) beyond your longest toe for comfort and proper gait. Tight shoes can cause blisters, bunions, and nail problems over time.
6. Use the larger foot: Buy for whichever foot is longer. If there's a significant difference, use an insole to pad the smaller shoe slightly.

Why shoe sizes don't convert perfectly

Even within a single size system, there is no universal standard — only industry conventions. A Nike US 10 and an Adidas US 10 may fit differently because each brand uses its own last (the 3D foot mould that determines the shoe's shape). Common sources of variation include:

• Last width and volume: A D-width (standard US) shoe fits differently than a 2E or EE (wide). European brands often run narrower; some American brands run wide.
• Running vs. dress vs. casual lasts: Athletic shoes add ~10–12 mm of toe box clearance; dress shoes are often cut closer to the last. The same foot can wear different sizes in different shoe categories.
• Half-size EU gaps: Because Paris Points don't align with US ⅓-inch increments, many brands offer only even EU sizes (40, 42, 44), which forces US half-sizes into a range (e.g. "40-41"). When buying EU-sized shoes, round up if you're between sizes.
• Country of manufacture: Italian sizing in particular often runs small; some Italian brands' "EU 40" fits more like an EU 39 by Brannock standards.

The conversions in this calculator represent the consensus across major international manufacturers and retailer charts. They are accurate for most brands but should always be cross-checked against brand-specific size guides when buying high-end or specialty footwear.

Buying shoes internationally

When ordering from an overseas retailer or buying in a foreign country:

• US/UK online retailers: Always verify whether the site uses US or UK sizing, the two are often confused on cross-border platforms. A UK women's size 6 is a US women's 8.
• EU retailers: EU sizing is unisex, so shop by foot length (cm) rather than trying to convert your gender-specific US/UK size.
• Japanese/Korean retailers: Sizes are in cm. Measure your foot and enter that number directly.
• Return policies: Always check the return policy before purchasing shoes internationally. Even with a correct size conversion, width and volume differences mean the shoe may not fit.

Kids shoe sizing: a different scale

Children's feet grow rapidly, up to two full sizes per year in toddlers. The kids' sizing scale is divided into three phases:

• Infant/Toddler (1C–13C): Sizes starting from approximately 9.9 cm (1C) up to 18.7 cm (13C), covering roughly ages newborn to 5–6 years.
• Little Kid / Youth (1Y–7Y): Continues from 13C, covering foot lengths from about 19.4 cm (1Y) up to 25.5 cm (7Y), ages roughly 6–12 depending on the child.
• Transition to adult sizing: At around 7Y (25.5 cm / men's US 7 / women's US 8.5), kids typically move into adult shoes. The exact transition depends on foot width; narrow-footed kids may fit adult shoes slightly earlier.

Because children's feet grow so fast, experts recommend measuring children's feet every 1–2 months and replacing shoes before they become tight; children often can't accurately report that shoes are hurting them.

Disclaimer

This calculator uses lookup tables based on the Brannock Device measurement scale and the industry-standard Paris Point EU system. Shoe sizing is not perfectly standardised across brands. These conversions represent the consensus across major manufacturers and should be verified against brand-specific size guides for high-precision fits.