Why don't you just get out a ruler and....oh....

Massive Size Comparison Charts.

The fun never ends.

Just recently saw a post covering Starship comparisons, I'm adding that and a few more....

Starships.

(Click to Enlarge, you might need to DL though)

Created by DirkLoechel [http://dirkloechel.deviantart.com/]

Movie Monsters.

(Click to Enlarge)

And of course
Giant Robots
(Click to Enlarge)