Pick a category and the region size you already know, and instantly see the matching size in Taiwan, Japan, Korea, the US, the UK, and Europe — no more guessing sizes while shopping abroad.
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A size label — whether a letter (S/M/L) or a number — is really just a code, and each region and brand decides independently what body measurement that code maps to. There's no single, globally enforced sizing standard. Japanese clothing sizing generally runs smaller than international sizing, so someone who's normally an international S might need to pick a Japanese M for the same fit — which is why a lot of travelers find themselves "buying an L at Japan's Uniqlo or GU when they normally wear M." Korea uses its own separate numbering system, covered in more detail below. Understanding that the same letter means a different size in different places is the most important mindset shift before shopping abroad.
Unlike clothing, shoe sizing does have one relatively objective common denominator: foot length in centimeters. Japan and Taiwan's shoe sizing is literally the foot length in cm (a size 25 roughly fits a 25cm foot); Korea uses millimeters instead (like 250), which is really just the same cm number multiplied by 10 — the same underlying logic. The US, UK, and EU each developed their own historical sizing systems (the US system traces back to an old "barleycorn" unit, the EU system to the "Paris point"), so the same foot converted into US, UK, and EU numbers can look like it follows no pattern at all. If you know your actual foot length in cm (measure heel to longest toe at home), matching it against this chart is far more reliable than memorizing any single country's size number — which is exactly why this tool's shoe tables are built around cm as the anchor value.
Even when two garments' tags both say "M" and the region conversion checks out perfectly, the actual fit can still differ a lot — because of cut. The same size label can use noticeably different amounts of fabric depending on whether the cut is loose (oversized/relaxed) or fitted (slim); fast-fashion brands, which prioritize low cost and fast style turnover, also tend to size more generously than premium or performance brands even under the same "M" label. So if you're shopping an unfamiliar brand abroad, it's worth checking that brand's own published size chart (usually with actual chest/waist measurements in cm) in addition to this region conversion — it'll be more accurate than a pure region conversion alone.
Shopping in Korea, you'll notice women's clothing often labeled with two-digit even numbers like "44, 55, 66, 77, 88." This is Korea's own legacy sizing system, originally built from combined height-and-bust measurements, and it roughly maps onto international XS/S/M/L/XL (44 ≈ XS, 55 ≈ S, and so on) — it's not random, there's a consistent conversion. For menswear, Korea commonly uses the chest measurement in cm directly as the size number (like 95, 100, 105) — the bigger the number, the roomier the cut. For jeans and casual pants, younger Korean brands increasingly just print the waist size in inches (like 26, 27, 28), exactly the same logic as US/UK sizing — which is why this tool's bottoms tables use waist-in-inches as the anchor value; matching the inch number directly is far more reliable than guessing a letter size when buying jeans.
This chart reflects widely accepted, relatively stable industry-standard conversions, and works well as a starting reference for shopping abroad or ordering internationally online. But keep in mind that cut and fit vary by brand, and online shopping means you can't see or touch the actual garment — before ordering, it's worth checking that brand's own detailed size chart (actual chest/waist/sleeve measurements in cm) on their website, and reading reviews about whether an item runs large or small, rather than relying solely on a generic region conversion.
Because size labels aren't tied to any mandatory global standard — each brand decides what body measurement "M" maps to based on its own cut philosophy (fitted vs. relaxed) and its target customers' body data. Fast-fashion, performance, and premium brands can all label something "M" while the actual chest/waist measurements differ noticeably. This is a normal reality across the global apparel industry, not a conversion error — for unfamiliar brands, checking their own published cm-based size chart is the most accurate approach.
For shoes, your own foot length in cm is the most reliable — Japan and Taiwan's shoe sizes are already in cm, and Korea's are the same cm number times 10 in mm, so the logic is straightforward. For clothing, if you know your actual chest/waist measurement in cm, matching it directly against a brand's own cm size chart beats a generic "S/M/L conversion." If you only know your usual letter size, this chart gives you a reasonable direction, but trying it on whenever possible is still the safest bet.
This tool currently only covers adult men's and women's clothing and shoes. Kids' sizing is usually based primarily on height (cm) or age, growth rates vary hugely between individual children, and different kids'-wear brands use especially inconsistent sizing logic — forcing a simplified region conversion here would risk misleading parents into the wrong size. We'd recommend checking that specific brand's own height-based kids' size chart, or trying the item on in person.
No. Every category, region, and size value is fixed reference data hardcoded into the page. The entire conversion runs 100% locally in your browser — there's no connection to any external server to look up or send back data, and nothing is retained after you refresh the page.