Sigma SD15 weighs 750 g (1.65 lb / 26.46 oz) and has external dimensions of 144 x 107 x 81 mm (5.67 x 4.21 x 3.19″). Considering that the average weight of DSLR type cameras is 769g, its weight is about average in its class. With a thickness of 81mm, it also has an average thickness.
Here is the front and top view image of Sigma SD15 with the dimensions:
In order to give you a better idea about the real life size of Sigma SD15, 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 Sigma SD15 with its main competitors:
Sigma SD15 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.