The area that gets warm is 15" x 10.5"
This heating pad only puts out heat along the center columns of rock: about 1" wide x 10.5" long column of rock with a 0.75" space between the columns of rock. There's a 2.5" border around the edges of the pad which doesn't heat and isn't highly flexible. It works ok on your back but can't be used on the tummy unless you're lying flat on your back. The area that gets warm is 15" x 10.5". It works alright in the sense that you plug the pad in, select the temperature and timer length, and it heats up. However, I had the pad on my lap, a pillow on top, and my Kindle on top of that (several inches above the back of the pad). I noticed that the battery power on the Kindle dropped 10% in just a few minutes (which is really, really fast) and I had to reboot the Kindle to fix the battery drain. It seems like the pad messed with my Kindle's battery which makes me wonder what it's doing to me. Natural jade sounds good, but they're using electricity to heat the stones to being with.
Rating: 3 stars