Join Date: Aug 2009
Location: New South Wales, Australia
Round yard size varies with what you want to do. For ground work often smaller is better, but for riding bigger is better.
Our round yard is a bit over 14m which is about what yours would be too. It's fine for groundwork and great for trotting, but while horses can canter on free lunge, an unbalanced or larger one might have difficulty and I wouldn't recommend riding at a canter on any horse that wasn't well balanced and used to it being that tight.
Saying that, once you're riding a horse at the stage where you'd want to be cantering in a round yard, you'd also probably want to be riding in a bigger area.
So it depends what you want it for. If it's just groundwork, the occasional ride around maybe or riding a younger horse, then I think that size is fine. For general riding, it's too small and you'd probably want to look at something heading more to arena sizes.