Hook Sizes: US and UK terns
Crochet has multiple terms to describe the same thing, but with hook sizes, we outdo ourselves! There are at least 3 ways to denote a hook size – a metric millimetre sizing, a US letter (sometimes a number) or a UK number are the most common.
(There are actually 4 types if you include Japanese sizes which are different again but I haven’t included that here for fear of information overload!)
Personally, I always stick to the metric mm sizing in my patterns. In a lot of modern western patterns you will be likely to just see the metric and or US sizes but there are still a lot of vintage UK patterns floating around so it’s useful to be aware of the options.
Here’s the table to help you translate!
What hook size matches what yarn weight?
Standard information about yarn weights in the US can be found here. It’s worth noting though that outside the US, different terms are used for similar yarn weights.
On top of that, weights can vary even within categories, so please use the below as a guide only and remember that meeting gauge is more important than hook size!!
You will often see a hook size recommended on the ball band (though sometimes it will only suggest a knitting needle size and ignore us crocheters all together!). Please remember that this is just a recommendation, so don’t be beholden to it!
We all crochet with a different tension too which impacts what hook we might want to choose so it’s not possible to make this an exact science!
Below is a table with a range of suggested hook sizes for each of the main yarn weights. However, there is no global standard because so much depends on the pattern you are working.
I have created this chart based on my experience and the range of hooks for Light and Medium weight yarns differs from the Yarn Craft Council.
I’m going to add one last caveat here. That is that for garments, I almost always go up a hook size or several sizes to that recommended on the ball band of the yarn I am using as this creates a more drape fabric.
Ultimately, experience will help you determine what size hook works best for you and the pattern you’re working, but in the meantime make a gauge swatch!