—
Metric (mm)
—
US size
—
UK/old size
| mm | US | UK/old | Typical yarn weight |
|---|
About Crochet Hook Converter
Hook sizing is not standardized globally. Metric (mm) is the most precise and recommended standard — always check the mm size, not just the letter code, as US letter assignments can vary by manufacturer. UK hooks use a numeric system where higher numbers = smaller hooks (opposite of US). Always swatch to verify gauge regardless of the hook size stated in the pattern.