Maine Coon is a breed of domestic cat. They're usually pretty big. The biggest specimens weigh up to 25 pounds—11.3kg. But Rupert here isn't just pretty big. He's huge. He's a "mega monster cat," according to the experts.
Heck, this thing can probably kill you if he decided to. He may become the biggest domestic cat in the world.
Rupert is now 20lb (9 kilograms) which is less than his biggest cronies. But he's only two years old. By three he will be much bigger, say the vets, growing to the point in which he would be at least 31 pounds (14 kilograms). Maine coons' growth levels at 9 to 14 months, and then they keep fleshing out till the age of 3 to 4.
For comparison, a wildcat like the male bobcat can get up to exactly the same weigh that Rupert is going to be. The Canada lynx goes only up to 24 pounds, while the Iberian lynx can reach 28 pounds. Only a male specimen of the Eurasian lynx would be bigger than Rupert, at 40 to 66 pounds.
Still, Rupert will be 31 pounds of muscle, teeth, and claws, a domestic cat of unknown origins who looks pretty much like a real lynx. I'm not sure if I could feel safe around one. [Maine Coon Growth, Wikipedia and Daily Mail]