Nikon D1 weighs 1200 g (2.65 lb / 42.33 oz) and has external dimensions of 157 x 153 x 85 mm (6.18 x 6.02 x 3.35″). Considering that the average weight of DSLR type cameras is 774g, Nikon D1 is a significantly heavy camera for its class. With a thickness of 85mm, it has an average thickness.
In order to give you a better idea about the real life size of Nikon D1, we have added an image of how it looks next to a credit card and an AA type battery.
Now lets compare the weight and thickness of Nikon D1 with its main competitors:
Nikon D1 doesn't have any environmental sealings on its body so you got to be extra careful to protect it against water and dust. If you shoot under these conditions very often, consider checking Top DSLR Cameras with Weather Sealing page.