It's stated that at 100 feet tall that he's able to lift 50 tons, is that realistic or just made up? What would his strength realistically be at 100 feet in height? 
 
Also, what of Ultimate Giantman's strength? I recall he can only become 60 feet tall at max since realistically that's when the human body wouldn't be able to support itself, so what's his general strength limit?

A year and a half later and no replies? Where are all of the nerds at?

Giant-Man is strongest at 12 feet, after twelve his strength is lost so as to help support his body, I would almost say that 50 tons would be about right at 100 feet, at twelve he is near 100 class, probably more at 85-90 but pretty close, Ill get some images to try and show everyone why I feel that way. As far as Ultimate Giant-Man I do believe he is class 100, but once again Ill have to do some research to confirm.

See, I thought that his strength was proportional to his height. So if he can bench, say, 200 lbs at 6 feet, it'd be 3,333 lbs at 100 feet... But now after doing the math, that's kind of weak compared to the other heroes...

Ya marvel didn't use any math and just put him at 50 tons at 100 feet, where that strength came from is unknown, using a math formula I came up with a formula of 111% increase to strength every 6 feet. Marvel stats make absolutely no sense, at 10 feet Pym can lift roughly 1000lbs according to the handbook, however he has been shown to do so in excess at that height. a more realistic number at 10 feet would be 5-10 tons, as Cap can lift 1000lbs, and Giant-Man has shown to be quite stronger than Cap.

@gambit1024: No, strength doesn't increase quite so fast as size does.

@ultimatedeadpool: Ok, using the square cube law, realistically:

If Giant Man's normal height is 6' then him increasing to 100' will mean he's grown by a square factor of 16.666... now strength increases by square factor meaning we have to square this to get the strength increase factor which turns out to be 277.777... Now the average untrained man can deadlift around 155 lb but we'll give Hank the benefit of the doubt and say he's a novice trainer able to deadlift 290lb. Multiplying this value by the strength increase factor we get 80,555.555... lb or 40.2777... tons, so they weren't too far off.

@hulksmash134: Hank Pym has the strength of a man his age, height, weight, and build who participates in intense regular training, so saying he has the strength of a novice trainer sounds kind of lowballed for him. Just saying. I'd say since he does intense exercise, he should deadlift about...227 kg (or 500 lbs).