Crochet Hook Size Converter
Convert hook sizes between US letter, metric (mm), and UK/Canadian systems.
Quick Converter
Standard Hook Sizes — Full Reference Table
| US Size | Metric (mm) | UK / Canadian |
|---|
Steel Crochet Hook Sizes (Thread/Lace)
| Steel Size (US) | Metric (mm) | Notes |
|---|
How to Use This Converter
- Use the Quick Converter at the top — select your size system and the hook size, and see all equivalents instantly.
- Use the search box above each table to filter rows as you type. Type a US size like "G/6", a metric size like "4", or a UK number like "8".
- Standard hooks (B/1 through S/19) are for regular yarn. Steel hooks (sizes 00–14) are for fine thread and lace work.
Understanding Hook Size Systems
- US: Uses a letter/number combo (B/1, C/2…). Larger letters = larger hooks.
- Metric (mm): The most precise system — measures the actual shaft diameter. Used internationally.
- UK/Canadian: An older numbering system where higher numbers mean smaller hooks — the opposite of the US system. Less common today.
- When patterns list only one system, use the mm measurement to match accurately.