We've got an 18" above ground, with an approx 5' step leading outside of the pool. So the shape is irregular, and at it's widest point is approx 23'. Last year I just used an 18' cover, and then a separate tarp to cover the step portion. This ended up letting a lot of leaves and nasty water in. This year I was going to get a 24' round cover, and just have a ton of extra in one dimension, and have it just a little over in the step direction. Figured I'd ask here before buying to see if there wasn't a better way to go.