About ConvertSizes

ConvertSizes is a free size-conversion reference for shoes, clothing and rings. It is run as an independent project, not by a retailer, so there is nothing to sell and no reason to flatter a number to close a sale. The site exists to give a straight answer to one question: what is my size in another country's system.

Where the numbers come from

Every conversion is generated from one function that works from a measured base, foot length for shoes, bust or chest for clothing, and inner circumference for rings. That base is mapped to each regional size using the published standard that defines it, from ISO 19407 for shoe conversion to EN 13402 for clothing and ISO 8653 for rings. The full list, with editions, is on the methodology page.

What the site covers

• Shoe sizes across US, UK, EU and centimetre scales for men, women and kids, including the reverse conversions and the points where the scales break.
• Clothing sizes across US, UK, EU and international letters, tied to body measurements rather than garment cut.
• Ring sizes across US, UK and the ISO millimetre scale, with the diameter and circumference behind each number.

Why it can be trusted

Because a single function drives every page, the tables agree with each other by construction. Each standard is named openly, so the figures can be checked against their sources rather than taken on faith. Where a conversion is not exact, the page says so instead of inventing a clean number.

Report an error

Spotted a number that looks wrong? Email hello@convertsizes.com with the page and the detail, and the rule behind it will be checked against the standard it follows. Reader corrections are the main way errors are found and fixed.