Why Korean sizes need converting
Korea uses body measurements as labels. Shoes carry the foot length in millimetres, men's shirts carry the chest in centimetres, kids' clothes carry the child's height, and ring sizes follow the Japanese 호 (ho) scale. Women's clothing uses the older 44 · 55 · 66 · 77 · 88 scale, which came from a 1981 national standard built around a 155 cm tall woman with an 85 cm bust (hence “55”).
US sizes are different in kind: letters (S/M/L), numeric dress sizes (0–16), Brannock-based shoe numbers and a ring scale measured in 0.8 mm diameter steps. None of these line up with Korean numbers directly, so a conversion table is the quickest way to shop confidently in either direction. Each converter on this site also explains how to measure yourself, so you can start from your body rather than from a label.
How these tables were built
The conversions are derived from published standards and widely used generic conversion data. Examples are the Mondopoint foot-length system, the ISO ring-size definitions and standard US body-measurement charts; nothing is copied from any brand's size chart. Where the market uses two conventions, we picked the one most common in Korea and say so on the page.
Sizes still vary by brand. Always check the seller's size chart, and when a listing shows measured garment dimensions (실측), trust those over the label.