Measure twice, make once
Crochet hook converter
Look up Craft Yarn Council metric and US sizes for regular and steel crochet hooks.
The page shows its formula, example, assumptions, rounding, and limitations beside the calculator.
Crochet hook converter
Look up Craft Yarn Council metric and US sizes for regular and steel crochet hooks.
Limits and rounding
Millimetres are authoritative. US labels vary by manufacturer, steel hooks use a separate reverse-numbered system, and blank US entries mean the CYC table gives no equivalent. Pattern gauge still decides the working size.