Nikon D3000 weighs 536 g (1.18 lb / 18.91 oz) and has external dimensions of 126 x 97 x 64 mm (4.96 x 3.82 x 2.52″). Considering that the average weight of DSLR type cameras is 774g, Nikon D3000 is a remarkably light camera for its class. Even better, with a thickness of only 64mm, it is also quite small, 12mm thinner than the average of its class.
Here is the front and top view image of Nikon D3000 with the dimensions:
In order to give you a better idea about the real life size of Nikon D3000, we have added an image of how it looks next to a credit card and an AA type battery.
Now let's compare Nikon D3000 size with the camera that it replaced: Nikon D40. Nikon D40 is 2mm narrower and 3mm shorter than Nikon D3000 but they have the same thickness of 64mm.
Below you can find the comparison of the weight and thickness of Nikon D3000 with its main competitors:
Nikon D3000 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.