WPI is short for wraps per inch. As simple as it is, you wrap your yarn around a ruler or a knitting needle and count how many wraps there is per inch. The WPI-method is good to use when you are working with a yarn that doesn’t have a gauge written on the tag. What you use it for is to figure out what size knitting needle you need to get a nice piece of textile. This method is good for handspun yarns and yarns you’ve lost the wrapper to.
If you are working with a handspun yarn that varies a lot do a lot of wraps so that you can do an average. Find either a medium size strand of the yarn, if you don’t have a such place do wrap count on both the thick and the thin part or you can work solely from the thick part. The result of using only the thick part will be large stitches when the thin part appears.
Personally I do an average and combine it with a little more gravitation to the thick part than the thin. That way I get a piece that isn’t too tight in the thick yarn. For this pattern I wouldn’t do something that is too see-through in the thin parts, as the mitten would have cold “patches”.
A piece of knit knitted on too small needles makes a hard and tight textile – a piece of knit knitted on too big needles makes a softer and very open textile. This can of course be used to create effect.
How to use the WPI-method
SO, how do you do this? Well as the method tittle says: wrap around your measuring tool and then you count the amount of times the yarn is wrapped with an inch. You can in my chart see how many wraps pr inch is what type of yarn, and what needle size you need.
Tip: If I have a yarn that varies in weight or I’m just in doubt if I counted right (I sometimes get confused to wether I cram the yarn too much to fill out the inch – especially on the tools that allows only an inch) I use a needle to wrap around. Use a needle size thats not too small at it’s easier to hold on to 😉 I then wrap more than just an inch and use my ruler.
Tools you need
You need either a ruler or a ruler and a knitting needle but you can also find little tools for just this method. They come many different shaped and materials and you can do them yourself. Here is a little picture roll with different tools. Some are done in wood or bamboo, they exist in plastic as well and you can fashion one yourself in cardboard like the fourth picture here. The tools have both advantages and disadvantages.
The tools that has a ‘confined’ inch makes it easier to control your wraps but also they don’t allow you to make more wraps than an inch to measure. Just as in a knitted gauge sampler you need to knit more than the 4″ to see how the gauge is. By wrapping more than an inch you can get the yarn to lay down nicer and get a more accurate wrap count. A tool that allows for 1.5-2″ wrap around is ideal in my mind.
Personally I prefer just my ruler as it’s the simplest way to do it. Plain an simple. I always bring it with my knitting projects anyways and as I travel a lot and commute daily too I don’t want to bring with me more than I can get by with.
You can also find electronic help. For example the iSpin Toolkit app (for about $5.5). It contains several features and also a WPI. Here is a picture of it in use.
Happy wrapping those inches!