This is the scale I use for all of my stuff, all of my vectors, baring a few early ones, have the right scale to them among each other. I often recycle parts and objects between worlds, so an object may seem big to a pony but looks just right for a human, and is indeed the exact same piece for both vectors. You can conceivably take a few random vectors of mine and slap them into the save canvas with zero resizing and the scale would be perfect. pedantic, perhaps, but it's how I am and what I like to do. Ponies are small, but even still, tall ponies are fairly large.
The only actual numbers are under the humans because they have confirmed sizes, obviously. :P I'm just gonna ignore all the fans pestering Oliver about his height, he calls them 'pussy holes' for doubting him.
No vectors used here are new to the site, so I just uploaded a PNG.