Shoe Size Calculator (Free, Accurate & International)

Shoe Size Calculator, Shoe Size Chart, Guide & How to Measure Shoe Size (US, UK, EU & International)

Between 63 and 72 percent of people wear shoes that don't correctly fit their feet — in either length or width. Most people only discover this after a painful blister, a heel slipping out mid-walk, or returning a pair they ordered online. This free shoe size calculator works as a complete foot measurement calculator: enter your foot length and it instantly converts your measurement into accurate sizes across every major international system — US men's and women's, UK, EU, Japan, South Korea, Australia, India, and Mondopoint. It also includes brand-specific guides for Nike, Adidas, New Balance, Converse, Vans, and others, because what shoe size am I in one brand and what shoe size am I in another are genuinely different answers at the same foot length.

What Is a Shoe Size Calculator — and Why Doesn't Standard Sizing Work?

The short answer: shoe sizing was designed for last-making, not for shoppers. The barleycorn unit that underlies US and UK sizing is literally a grain of barley. The EU Paris Point is 2/3 of a centimetre. Neither system was designed for international cross-reference or online shopping — which is why you need a calculator rather than a simple chart lookup.

A shoe size calculator converts a direct physical measurement — your foot length in centimetres or inches — into the size codes shoe manufacturers use across different countries. Sounds straightforward. But here's the thing: there is no single global shoe sizing standard. The US, UK, EU, Japan, South Korea, Australia, and China all use different numbering systems with different starting points and different increments per size. The same foot gets described as a US 9, UK 8, EU 42–43, and a 270 Mondopoint — all correct, all different numbers. This free online shoe size calculator resolves that problem instantly, working as a complete foot measurement calculator across all systems simultaneously.

You'd expect your shoe size to stay consistent once you know it. It doesn't — not across countries, and honestly not always across brands within the same country either. A peer-reviewed systematic review in the Journal of Foot and Ankle Research, examining 18 studies across multiple countries, found that between 63 and 72 percent of participants wore shoes that didn't fit correctly in length or width. More than 60 percent of people are wearing incorrectly sized shoes right now — not because they don't care, but because sizing systems are inconsistent and most people were last properly measured as children.

A lot of people realise this after ordering two sizes and returning both. If you've ever had your heel slipping out mid-walk, or noticed your toes pressing the toebox after an hour — this is exactly why.

The international standard that attempts to fix all this is Mondopoint (ISO 9407:2019). It defines shoe size as foot length in millimetres — no arbitrary offsets, no gender adjustments, just your actual measurement. Japan, South Korea, and China use Mondopoint as their primary system. Most athletic shoe brands now include CM measurements on their labels. Honestly, Mondopoint is the only sizing system that makes complete logical sense. Knowing your CM foot length is the single most reliable cross-brand reference you can have — especially when using this tool as a shoe size calculator for online shopping, where you can't try before you buy.

How the Shoe Size Calculator Works — The Formulas Explained

Every shoe sizing system ultimately references the same thing: the length of the foot. The differences are entirely in how that measurement gets expressed — which unit, which mathematical increment, where the scale starts. Once you understand the logic, the conversions stop feeling mysterious.

The Core Measurement — Foot Length

Your foot length is the straight-line distance from the back of the heel to the tip of your longest toe. That's it. This foot size calculator uses that single number as the input for every conversion. It deliberately does not use a size from another brand — that would reintroduce the brand-specific variation this tool is designed to eliminate. Your foot length in centimetres is the universal reference point. Everything else follows from it.

US Sizing Formula

The US system is based on barleycorns — an old English unit equal to 1/3 inch (approximately 8.47mm). Each full size change equals one barleycorn of foot length. US men's size 1 begins at a last length of approximately 7.33 inches (186mm). The US women's system starts two sizes lower than men's — a US women's 8 and a US men's 6.5 correspond to the same foot length. This is why the men's shoe size calculator and the women's shoe size calculator produce different numbers from the same foot measurement. US sizing is probably the most confusing system for international shoppers for exactly this reason.

UK Sizing Formula

The UK system uses the same barleycorn increments as US but starts at a different reference point — giving the consistent one-size offset for men (US = UK + 1) and two-size offset for women (US women's = UK + 2). Unlike the US, UK sizing doesn't split by gender in the numbering. One scale applies to everyone. Australia and India follow the same UK conventions exactly.

EU Sizing Formula

EU shoe sizes use Paris Points — units of 2/3 centimetre (6.67mm). Because the EU increment is smaller than the US/UK increment (8.47mm), one US size can span one and a half EU sizes. In theory, this conversion works cleanly on a chart. In reality, it means a US 9 might be EU 42 or EU 43 depending on the specific brand's last. The calculator shows both adjacent EU sizes so you can cross-check against the brand's own chart — this is where most EU conversion errors happen, and it's the right way to handle it.

Mondopoint / Japanese / Korean / Chinese Formula

These systems express size directly as foot length in millimetres (Korea) or centimetres (Japan, China). A Mondopoint 270 means the shoe is made for a 270mm foot. No arithmetic. No offset. The number is your measurement. This is why footwear specialists consistently recommend using CM as your cross-brand reference — it bypasses the US/UK/EU arithmetic entirely. If you know your foot is 27.0 cm, you can apply that to any brand's CM chart without any conversion at all.

International Shoe Size Chart — Complete Conversion Table

One thing I want to flag before you read this table: EU sizing is based on last length, not foot length. The shoe's internal form (the last) is always 10–15mm longer than your foot. This is already built into this calculator, but many comparison charts online skip that step — which is why you'll sometimes see EU 43 quoted for a foot that should really be EU 42.

This shoe size chart covers the full adult range for men's and women's shoes across all major international systems. All values are derived from ISO 19407:2023 and ISO 9407:2019 (Mondopoint). Foot length values are given in millimetres.

Women's Shoe Size Conversion Chart

Men's Shoe Size Conversion Chart

Source: Values derived from ISO 19407:2023 and ISO 9407:2019. EU sizes can span half-size ranges because EU increments (6.67mm Paris Points) are smaller than US/UK increments (8.47mm barleycorns). Always cross-reference against the specific brand's published size chart — particularly for EU conversions where the range spans two sizes. India uses UK sizing directly; Indian sizes match UK sizes exactly. Australia uses UK sizing with the same numerical values.

Shoe Sizing Systems Explained — US, UK, EU, Japan, Korea, India, Australia

Japan's Mondopoint system is actually the most honest of all: it's just your foot length in centimetres. No multiplier, no offset, no historical unit. A Japanese size 27 means a 27cm foot. If every country used this, shoe shopping across borders would be trivially simple. The EU Paris Point and the US barleycorn systems have survived purely through retail inertia.

US Shoe Sizing

The American shoe sizing system uses barleycorn units (1/3 inch / 8.47mm per size) and differs between men's and women's. Men's sizes run one higher than UK; women's sizes run two higher. Half sizes are standard. The US system also has a width coding system: for women, B is narrow and D is wide; for men, D is standard and 2E or 4E are wide widths. The Brannock Device — the metal foot measuring tool found in shoe shops — was invented in 1925 and remains the professional US measuring standard. US sizing is, genuinely, one of the more confusing systems for international shoppers, largely because the gender-based split means the same number means two different foot lengths.

UK Shoe Sizing

The UK system uses the same barleycorn increments as US but starts from a different reference point — giving the consistent one-size offset for men (US = UK + 1) and two-size offset for women (US women's = UK + 2). Unlike the US, the UK scale doesn't split by gender. One number, one scale, no gender offset. Australia, New Zealand, and India all follow the same UK conventions. So if you're wondering how to convert shoe size from US to UK: for men, subtract 1. For women, subtract 2. That's the whole formula.

EU Shoe Sizing

The European system is based on Paris Points — one Paris Point equals 2/3 of a centimetre (6.67mm). Since this increment is smaller than the US/UK barleycorn (8.47mm), a single US/UK size can cover one and a half EU sizes. This is why EU conversions are expressed as ranges (EU 42–43 for a US 9) rather than single numbers at certain foot lengths. On paper, this conversion works. In practice, it means you sometimes end up between two EU sizes — and the right one depends entirely on which brand's last you're wearing. Many European brands produce half EU sizes to handle exactly this situation. Always verify against the brand's own CM chart rather than relying on a generic conversion table, particularly at half-size boundaries.

Mondopoint — Japan, Korea, China

Mondopoint (ISO 9407:2019) expresses shoe size as foot length in millimetres or centimetres. Japan uses centimetres (27.0 = 270mm); South Korea and China use millimetres (270). This is genuinely the most rational system of the lot — the number is your actual foot measurement, no offset, no conversion formula. Footwear specialists consistently recommend using CM as your cross-brand reference because it sidesteps the US/UK/EU arithmetic entirely. If you need a cm to shoe size calculator specifically, this is the section to bookmark: your Japanese size is your foot length in cm, and your Korean size is that same number in mm.

Indian Shoe Sizing

India uses UK shoe sizing directly — so if you already know your UK size, you know your Indian size. An Indian size 7 is a UK 7. Major Indian footwear brands — Bata India, Liberty, Metro Shoes, Woodland — all use UK conventions. International brands sold in India (Nike, Adidas, New Balance) use their standard US or EU sizing with conversion charts. For online shopping on Myntra or Flipkart, UK sizing is the reference standard. This shoe size calculator outputs Indian size alongside UK since the numbers are identical — no separate calculation needed.

Australian Shoe Sizing

Australia uses UK shoe sizing conventions with the same numerical values. An AU 8 and a UK 8 are the same size. The only complexity arises from US brands, which may label the Australian market product in US sizes — requiring the standard one-size (men's) or two-size (women's) adjustment. New Zealand and South Africa use the same UK/Australian conventions.

Brand-Specific Shoe Sizing Guide — Nike, Adidas, Converse, New Balance & More

I've watched this cause a full-size return more times than I can count: someone buys Nike in their usual size, finds them too tight, then orders the same size in Converse thinking it's the same. Converse runs a full size large; Nike runs half a size small. The combined error is 1.5 sizes. The rule is simple: always go back to your foot length in cm, not your "usual size in another brand."

Your calculated shoe size is the starting point — not the final answer. Every brand uses a slightly different last (the internal foot-shaped mould), and this creates real, measurable differences in how shoes from different brands fit at the same nominal size. You'd expect a US 10 to be a US 10 everywhere. It isn't. The golden rule recommended by footwear fitting specialists: use your CM/Mondopoint foot length as your cross-brand reference, because it represents your actual foot rather than an abstract scale position. This is where most people mess up when shopping online — they convert their existing brand's size instead of going back to the raw foot measurement.

For brand-specific conversions, the Nike Shoe Size Converter handles Nike-to-international conversions with model-specific notes, and the Nike to Adidas Size Converter accounts for the documented half-size difference between those two brands. For UK and EU cross-system shopping, the UK to US Shoe Size Converter and EU to UK Shoe Size Converter target those specific lookups.

Which Sizing System Works Where — Coverage Chart

Different sizing systems work well in some contexts and poorly in others. Here's a quick breakdown — useful to know before you start converting between systems you haven't used before.

⚠️ "Partial" ratings reflect situations where conversion produces correct results most of the time but occasional half-size discrepancies occur due to scale increment mismatches. Mondopoint is rated "Yes" for US and UK because any brand using those systems publishes a CM chart that Mondopoint maps directly onto.

Related Sizing Tools

Shoe sizing is one dimension of a complete size picture. These tools extend the same precision approach to every other measurement:

• For a general cross-system conversion from any foot length, the Shoe Size Converter handles all international systems simultaneously. The Sneaker Size Converter applies the same logic with a focus on athletic footwear.
• For brand-to-brand conversions, the Nike Shoe Size Converter handles Nike-to-international with model notes, and the Nike to Adidas Size Converter accounts for the documented half-size gap between those two brands specifically.
• For cross-country conversions, the UK to US Shoe Size Converter and EU to UK Shoe Size Converter target those specific lookups.
• Body measurement tools: The Body Measurement Calculator extends the same measurement precision to the full body.
• Other accessories: Complete your sizing picture with the Ring Size Calculator — both use the same measurement-based approach.

Frequently Asked Questions

Scientific Sources & References

The sources below are the same ones this calculator's formulas are derived from. If you're comparing against a competitor's tool, ask them for their methodology source — most don't have one.

All sources below are real, peer-reviewed publications or official institutional standards with working links verified at time of writing.