# Crochet hook converter

> Look up Craft Yarn Council metric and US sizes for regular and steel crochet hooks.

- [Open tool](https://threadcabin.com/tools/crochet-hook-converter)
- The page shows its formula, example, assumptions, rounding, and limitations beside the calculator.

## Formula and assumptions

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.

## Limits and rounding

Results are planning estimates from the values entered. Displayed decimals are rounded for craft use; whole materials and repeats round up where the method says so. Confirm gauge, material behavior, construction, and finished measurements before committing supplies.

- [Craft Yarn Council hook and needle standards](https://www.craftyarncouncil.com/standards/hooks-and-needles)