Raw. 285g uncooked is not going to be 285g cooked.
It will probably be 240g (best guess, I don't know for sure) but it depend on how much you cook it (ie. if you cook it just to the point of being done or dry the fuck out of it) and how you cook it.
It's around half a pound (cooked) which is not much at all. That's one small-medium sized chicken breast or about 2-3 bites.