[AmityvilleHams]

There's not really one set minimum,but if we're basing it off a good standard comparing it to the equivalent of a 6 inch long Syrian in a 1,550 square inch cage is giving about 258.3 square inches per inch of hamster.Going from there with the maximum robo length you get 258.3x2,or 516.6 square inches.Something like half a Detolf could work well,and you could use the other half for another robo or a Chinese hamster or even as a transition size for another dwarf species or Syrian.