Everyone crochets slightly differently. This is due to tension. Which is why when you see a pattern done by different people the finished products are always slightly different. What gauges allow you to do is match up your tension to the pattern’s creator. So you can make the project to the correct size.
Gauges are crucial when you’re making clothing. For amigurumi it’s not really necessary. Unless you do one of my kits. In my kits I include a gauge so you can make sure that the yarn included will be enough for your project.
How to Measure: Gauge
You’ll typically be given measurements for a square / rectangle piece. It’ll tell you how many sc/dc/tc per row and how many rows to make. It will then give you the measurement (inches) of what you’re square should be.
So for example:
10 sc = 3’’
12 rows = 3’’
Make a piece that is 10 single crochet long. Make 12 rows. Take out your ruler and measure your piece. If your piece is smaller than 3″ switch to a larger hook and try again. If your piece is larger than 3″ switch to a smaller hook.
8 sts and 4 rows of dc = 2″
Make a piece that is 8 double crochet long. Make 4 rows. Your piece should measure 2″. Same as above, if you’re piece is smaller switch to a larger hook; if it’s larger switch to a smaller hook and retry.