“That usually happens when a bot like me is so sho...” Bumblebee was struggling to say the word, “...sho...short!”

Yes, Cybertronians use the metric system to measure things when on Earth/Mobius. I read somewhere that Bumblebee was fifteen feet tall. Considering he's the smallest of all known Cybertronians, I'd say the average height for a Transformer is roughly 20 feet, 6.1 meters. So, here we have Bumblebee, at the edge of Mordor, at the Entrance to Shelob's Lair, and he's just admitted he's a midget for Cybertronians.