What is the usual/average size of a featherweight? A rough starting point width by length.

I know there's a weight limit and no real restriction but what size should I be looking at making my robot? I have looked and seen various sizes recommended on forums but they vary greatly. Yet in the videos on YouTube the robots all look a similar size.

I don't want to make a robot that fits in a cereal box that ends up squashed by something the size of coffee table.

How big is your robot?