A couple of years ago mikeyssmail (www.youtube.com/user/mikeyssmail) uploaded a video explaining how he chooses the loom he is going to use to when loom knitting a hat. Since I received a couple of questions asking how to choose which loom to use I thought this would be a good video to post here. In the video he simply places the loom on his head and chooses the loom that fits best. In the video he explains that the outside diameter of the loom will be the actual size of the project.
Take a look at how he chooses a loom.