Superman's lifting power changes a lot in the comics. It's not one number. It can seem endless. He does huge feats like lifting the Earth or towing a galaxy. Here are some indications of just how much he can lift.
Big Lifting Feats
Bench-press the Earth: In New 52, he lifted Earth's full weight (5.97 sextillion tons) for 5 days. No sun, and he was not tired at all.
200 quintillion tons: In All-Star Superman, a dying Superman lifted this much with one arm. He said he could do more.
Hold up everything: In Superman: Man of Tomorrow #12, he took Atlas's job. Held the whole DC Universe, that's all worlds, things, and people. Everything.
Tow a galaxy: Silver Age Superboy pulled a whole galaxy like it was nothing.
Why His Strength Changes
Writers explain the ups and downs like this:
Motivation: He gets stronger to save people. Holds back vs. weak foes. Goes all out vs. big threats.
Solar energy: Power from the sun. More sun = more strength. "Sun-dipped" means supercharged.
Holding back: He limits himself on purpose. Versus Batman, he pulls punches. He once hurt himself with a big punch by mistake.
Story needs: Some lifts are symbols, not real weights. Like lifting a book with infinite pages in a dream world.
For your Guardians game, don't pin Superman to one stat. Let strength scale with the plot. Need him to lift a planet? He can. Fighting street thugs? He holds back. Tie it to "will to protect" or sun points. Keeps things fun and true to the comics. Superman lifts what the story demands.
Looking for a more firm answer? Ok, here you go:
Superman can lift two billion tons in his normal form, but when he's supercharged, he can lift at least 200 quintillion tons!
