I am in a wheelchair. 20x30 would be perfect for me. You just want it big enough to cover, not wrap up in it. If it is to wide, then you have to tuck it in, and that could stick out the sides and get caught in the wheels unless it's a power chair. If it's longer than 30 in, it would for sure catch in the wheels. Just keep in mind, this is merely to keep the lap and legs a bit warmer, not to snuggle up in. I am missing one leg, and I hate wearing long pants because unless I hem the missing leg, it tends to get caught in the wheels in my manual chair, so I hem like it is a capri. And prefer capri's to long pants because of that reason. Hope this is helpful.