Using the correct gauge loom for a certain project and yarn can make all the difference in the world how the finished item will look when done. I encourage you to make notes for yourself when you make gauge swatches, so that you don't have to constantly repeat your swatches.
Different Loom Gauges
Different Loom Gauges
Most loom manufacturers state the loom gauge as a fraction of an inch. The measurement is the distance from the center of a peg to center of the next peg. You may see it written as C2C Space or C2C Gauge or just as Gauge.
The standard gauges used by various loom makers are in the following chart.
This chart is just a guide. For various types of yarns you can use a larger or smaller loom to achieve various looks. For example most lace is done with Fine yarn or smaller but using a larger loom to achieve the open, airy look. Another example is using Twisted Knit Stitches (ewrap) with a larger yarn on a smaller loom or using multiple strands of a smaller yarn on a larger loom. This chart doesn't cover the various ways to set up a double rake for double knitting.
Loom Knitting Patterns
If you are following a pattern specifically for loom knitting try to use the loom and yarn listed in the pattern. If that is not possible substitutions can be done and still achieve an item fairly close to the pattern. This takes some trial and error and some practice. Do a gauge swatch with the loom and yarn you wish to use to determine if it will work for that pattern.
Needle Knitting Patterns
If you are following a needle knit pattern get a yarn as close to the same weight as the one used in the pattern that you can get. Look at the size needles the pattern calls for and use the chart above to determine which loom to use based on the needle size in the pattern. I always suggest doing a gauge swatch and comparing it to the gauge measurement listed in the pattern. If your swatch is too big (your number of stitches is the same but it measures bigger in inches) use a smaller loom, and if your swatch is too small (same number of stitches but measures smaller in inches) try using a bigger loom. There is no fool proof way to get it exactly right.
I hope that the chart and notes I have here will help you get started. Remember to make notes for yourself as you go.