And you may want it worn at different heights on different occasions. For instance, when I'm wearing a vest, sweater, or pullover that covers the top of my kilt, I will generally wear my sporran a little lower than normal, so that it is completely clear of my upper garment.

If I am wearing the kilt without any of the above, with a belt (as I normally do), then I wear it at what I consider my "standard" position.

But if for whatever reason I don't wear a kilt belt, I'll wear my sporran a bit higher than normal, just because I think it makes the outfit look better without the belt.

All this is to say there is a range within the sporran should both look and feel comfortable.
Aye,
Matt