How big will my GSD be?

Hello,

I have a male German Shepard that is 5 months old. He weighs 40 lbs. How big should the dog weigh when he is fully grown? His paws are nice size but not very big. Please let me know. He eats three times a day. I give him natural ultra dog food for large breed dogs. Will he be 75 -80 lbs?? Fully grown?

Thank you!
Eddie