I saw this video in Japanese a while back, but now YouTube user MetroidSuperFan has translated it into English. It shows size comparisons of a lot of mecha, robots both real and fictional, astronomical objects (the mecha get really big), and various other objects for reference.
Things I noticed:
- The first giant robot in anime (Tetsujin-28/Gigantor), the first piloted super robot (Mazinger Z) and the first real robot (RX-78 Gundam) are the same height.
- For the giant ones from Transformers, they used anime size for Fortress Maximus (in the comics he’s not much bigger than other Transformers), but comic size for Unicron (cartoon Cybertron is smaller than Earth, and Unicron’s height is about equal to Cybertron’s diameter)
- Lagann is probably the smallest human-piloted mecha, and probably the only mecha to be shorter (post-timeskip) than its own pilot
- It was really hard for me to resist overtagging this