About SizeDecoder
SizeDecoder started from a specific annoyance: buying clothes or shoes from a store in another country and having no reliable way to know what size to click "add to cart" on. Search engines return scattered retailer charts that disagree with each other, a dozen near-identical "size converter" tools with no real explanation of why the numbers don't line up, and almost nothing that tells you the honest answer — that no conversion table can promise you a perfect fit, because sizing systems weren't built to translate into each other and brands don't follow them consistently anyway.
What this site actually does
Two things, done properly instead of half-heartedly. First, instant conversions between US, UK, EU, Japanese, Korean and Australian sizing for every garment type we could find real, standard conversion data for — shoes, dresses, shirts, jeans, bras, rings, hats, gloves, socks, belts, suits, kids' and baby clothing, swimwear, and a handful of activity-specific categories like ski boots and wetsuits. Second, a set of practical measuring guides, because a conversion table is only as useful as the number you're feeding into it. If you don't know your actual chest, waist, or foot length, converting a size label from one country's convention to another just moves the guesswork around instead of removing it.
What we won't pretend to do
We won't tell you a conversion table guarantees fit. It doesn't, and any site that implies otherwise is overselling a lookup table. Vanity sizing, brand-specific cuts, and fabric behavior all mean the same nominal size can fit differently across two labels from the same country, let alone two countries. Every conversion and chart page on this site says so plainly and points you to the garment's own size chart as the final check, not this site's table.
Where the numbers come from
Every table is built from standard, publicly documented sizing conventions rather than scraped from a single retailer. The full sourcing and dating approach is on the methodology page.
Who this is actually for
Three kinds of visitor land here in practice: someone ordering a specific item from a specific overseas retailer right now and needing one number fast; someone who moved countries and is rebuilding a wardrobe reference from scratch; and someone buying a gift in a system they don't personally wear, like a partner's ring size or a child's shoe size in a country they've never shopped in. The site is built around the first two kinds of visit — a fast, specific answer, and a durable reference you can save — rather than around generic "fashion size guide" content that reads well but doesn't answer either question.
Why there's no login, account, or newsletter gate
Nothing on this site requires an account, and the one tool that stores your personal measurements (My Size Card) keeps them in your browser's local storage rather than on a server anywhere. A size conversion is exactly the kind of one-off lookup that shouldn't require handing over an email address to use, and building a login wall around free public conversion tables would only slow down the people this site is actually meant to help.
How the site grows from here
New garment categories get added when there's a real, standard conversion table to publish for them, not on a fixed schedule, and existing charts get rechecked against the maintenance cadence described on the methodology page rather than left to go stale. Every page published here is a finished page — the conversion and chart corpus on this site is the same depth throughout, from the first garment added to the most recent one.