Canon 550D weighs 530 g (1.17 lb / 18.70 oz) and has external dimensions of 129 x 98 x 62 mm (5.08 x 3.86 x 2.44″). Considering that the average weight of DSLR type cameras is 774g, Canon 550D is a remarkably light camera for its class. Even better, with a thickness of only 62mm, it is also quite small, 14mm thinner than the average of its class.
In order to give you a better idea about the real life size of Canon 550D, we have added an image of how it looks next to a credit card and an AA type battery.
Now let's compare Canon 550D size with the camera that it replaced: Canon 500D. As depicted on the comparison image, and have the exact same height, width and thickness.
Below you can find the comparison of the weight and thickness of Canon 550D with its main competitors:
Canon 550D 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.