Another handy built-in measuring device that came free with your body (Plus, if you're born in the next twenty minutes...) is the fact that your "wingspan" (the distance from tip of middle finger to tip of ther middle finger with arms outstretched is (in most people) almost exactly equal to your height. This provides another convenient way to measure rooms, furniture, etc. without having to lie down (and for six-footers like myself the math is easy, too!).