It depends not only on size, but on whether you have any pain issues. I have arthritis in my hips and at that time had bursitis in my shoulder. The mattress on the sofa bed wasn't thick enough for me. I added a topper, still not good. I ended up being able to sleep with strategically placed pillows. I wouldn't do it again though. For someone without pain it could be okay. The part under the mattress is solid, so you don't get the old roll into the middle that you used to get with sofa beds.