I think 13-18 lbs. is the average. I know someone that has a M. Coon that weighs 21 lbs. and it is not overweight, just a BIG kitty. I have a M. Coon kitten right now that is 8 months old and already weighs 12 lbs. They are big, gentle, affectionate cats. They are also smart and GOOFY at the same time! I love them!