Once during a phone call, my family needed to know the rough dimensions of something at my brother's house. He couldn't find a tape measure, but he had a jug of milk. We determined that the item we needed to know the dimensions of was the size of the height of my brother plus one milk jug.
This is completely ignoring perspective, and I'm also questioning the entire methodology how the length of this cat is measured. It's like measuring how tall someone is while sitting.