American vs. UK vs. Metric Hook Sizes
We’ve talked a little bit about yarn and how yarn sizes aren’t terribly consistent or precise. Well guess what? Hooks are unfortunately not much different.
There are US sizes, UK sizes and metric sizes. I personally prefer metric sizes, as that seems the most precise to me – a 4.0mm hook is a 4.00mm hook, whether it’s purchased in the US or the UK, and there are tools you can buy to verify that sizing. I have this one, and use it whenever I’m in doubt.
I made this handy little chart to help demonstrate all the different names of crochet hooks. This is for non-steel hooks, which are typically aluminum, wood, or plastic. Steel hooks are smaller than these and have a different sizing system altogether! Feel free to print this chart out for future reference.