How do people gauge a strength feat?

So I have had this question in my head since last night, but didn't post it cause I was going to bed. But....how are people gauging how heavy things are? Without it actually saying on panel or w/e....like how are people gauging that "such and such thing is X amount of tons."

Again without it actually saying on panel in a comic, anywhere. Just curious....is it just guess work or am I missing something?

Often times I believe people compare them to real world objects.

Say Aquaman lifts a cruise ship, people would probably then look up the average weight for such a ship and estimate his strength feat to be around that area.

I don't exactly know if that's how people do it, but it seems logical to do it that way.

@thetruebarryallen: That's what I was thinking....but I guess I just wanted to make sure.

Based on best estimates of what the things lifted or moved would weigh in the real world and, in cases where a powerful force is resisted or overcome, by estimating the influence that power would have in the real world, too.

A good way is to judge by surroundings. If someone flips over something that is shown to be larger than say, a building, you can get an estimate.

Pretty much this. (That's a 100,000+ ton feat btw ;P)