Size matters, when it comes selecting the right hook size for your yarn. (What were you thinking?)
But sometimes, some yarn balls come without information on the recommended hook size or you’ve lost the yarn label. No reason to fret. There’s a method to estimate the rough hook size compatible with a specific yarn weight category. It’s called Wraps Per Inch (WPI).
How does WPI work?
- Wrap the yarn around a ruler, ensuring that each strand sits cosily shoulder-to-shoulder with its neighbour and you do not see gaps between them but that they do not overlap (no holding hands!).
- Count the number of strands that cover exactly 2 inches, then divide that number by 2. The resultant number is the WPI for that particular yarn.
- Refer to Sewinlove’s Handy Yarn Conversion Table to find out the recommended hook or knitting needle size for your yarn-anon.
At the same time, I’ve had a few students ask: What’s 4-ply yarn? This terminology is more prevalent in NZ/AU, I find. It means a few things:
- 4-ply yarn is a yarn weight category that is also known as sock/fingering/baby.
- 4-ply yarn also means it is made up of 4 thinner strands of yarn twisted together to form its thickness. The more plies, the thicker and the bigger your hook/needle.
And what is the recommended hook/needle size for 4-ply yarns (or for a single-ply, or 12-ply yarn?) – again, you can rely on Sewinlove’s Handy Yarn Conversion Table to guide you.
My last bit of advice is to note that we all work with slightly different tension in our hands so you can up/down-size slightly from the recommendation to suit your work or intended effect.
I’ve worked hard to cobble together all this important information together in an all-encompassing and comprehensive conversion table, which isn’t found elsewhere (I think! Or at least I haven’t come across a similarly comprehensive one elsewhere), so please feel free to bookmark the page to come back to it whenever you need it.