What is a swatch?
A swatch is a small piece of knitting that is used to measure your gauge — the number of stitches in a piece of knitting 10cm wide. You can also measure your row gauge — the number of rows you have in a 10cm length.
If your gauge matches the gauge given in the pattern, then your knitted garment should be of the expected size. If you have more stitches per 10cm than the required gauge, and you just cast on the number of stitches given for your size, your garment will come out smaller than you want. If you have fewer stitches per 10cm in your swatch then your garment will be larger than you want. If your gauge doesn't match, change needle size as necessary, and knit a new swatch.
Benefits of swatching
- Firstly of course, you will find out if your gauge matches that expected in the pattern
- ...and therefore find out if you are going to make a garment that looks and fits as you hope
- It's a chance to try out the stitch patterns, so you make mistakes in the swatch rather than the real thing.
- It allows you to get used to a new yarn or stitch pattern, so when you come to knit your item you have a more even tension.
- You can decide whether you like the yarn and pattern before you commit to casting on a whole jumper's worth of stitches.
- Wash your swatch and find out how the fabric changes and whether you are making something that is easy enough to keep clean.
It can feel like a waste of time, but it's not when you compare it to knitting your sweater in the wrong size and only finding out when it's finished. Or when you wash it.
It's your choice, you're the knitter, and if you're knitting a shawl or a blanket and the finished object ends up 5 or 10% bigger or smaller, you may not mind. But before you decide not to swatch, at least understand what you're risking.
The more experienced the knitter, the more likely they are to swatch. That sounds counter-intuitive, but they probably learnt the hard way that getting to know a yarn is the vital first step to a successful project.