OK. So I am sure this has already been asked here but I can’t find it, so I am going to ask it again! Can someone please, please, please explain the gauge thing? I understand it when you are using the yarn suggested in the pattern, but what if you are using a yarn different from the one suggested? How do you figure out if its on target? I have been knitting for while but have never been one to do swatches as it hasn’t really been necessary. Now it is and I am confused!
It’s especially useful when you’re NOT using the yarn in the pattern. Start with your yarn and the needle size as given in the pattern. CO about 6-10 sts more than used in the gauge. This is because edge sts aren’t the same size and tend to curl under so you want some extra in order to measure 4" across the middle of the piece. If you have more sts per 4", it’s too tight and you need to go up a needle size - or 2. If there’s fewer sts per 4", it’s too loose and you go down a size or two. If you change needles and it’s still not right, you have a very different weight and need to think about using a different yarn or different pattern size than you think you need. If you don’t get the right gauge and have to change needles, you can just do a knit row on the wrong side and change the needle, you don’t have to make a different one for each. It can also help to wash and block the square like you will the finished item because some yarns can stretch a lot when wet. Take measurements before and after to see how much it changes if any.
I like the little saying at the bottom of your post. So true.
When I substitute yarns I like to try to use a yarn that has the same or close to the same recommended stitch gauge as the one called for. Look on the skein for the number of stitches the yarn you want to use gets and you can look at the skein of the yarn called for and see what it says (you can also look yarns up on the internet to find this sort of information). If they are similar it makes it easier. If they are way different then you will have major changes that have to be made to make that yarn work for that pattern.
After you have a yarn of a similar weight, then I do what Sue said. When you are working on the swatch ask yourself if the fabric you are getting with the new yarn has qualities that will produce the affect you are trying to get with your envisioned project.