Size and weight are big decision factors when you are trying to find the ideal camera for your needs.
In this section, we are going to illustrate the Pentax WG-1 GPS and Canon 550D side-by-side from the front, back and top in their relative dimensions. Pentax WG-1 GPS has external dimensions of 116 x 59 x 29 mm (4.55 x 2.3 x 1.12″) and weighs 167 g (0.37 lb / 5.89 oz) (including batteries). Canon 550D has external dimensions of 129 x 98 x 62 mm (5.08 x 3.86 x 2.44″) and weighs 530 g (1.17 lb / 18.70 oz) (including batteries).
Below you can see the front-view size comparison of the Pentax WG-1 GPS and the Canon 550D. Pentax WG-1 GPS is clearly the smaller of the two cameras. Its body is 13mm narrower, 39mm shorter and 33mm thinner than Canon 550D. As you can tell, actually this is not a fair size comparison since Pentax WG-1 GPS has a built-in lens but Canon 550D doesn't. Once you put a lens on 550D, its thickness will increase significantly.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Pentax WG-1 GPS is significantly lighter (363g ) than the Canon 550D which may become a big advantage especially on long walking trips.
Again, this comparison may not be very useful in real life as we are comparing the weight of a camera with a built-in lens to the body-only weight of an interchangeable lens camera. Once you put a lens on 550D, the total kit will weigh much higher.
Weather Sealing
Thanks to the weather-sealed body of the WG-1 GPS, you can use this camera with more confidence under conditions where there is risk of exposure to water and dust compared to the 550D.
LCD Screen Size and Features
Canon 550D's 3.00" LCD screen is slightly larger than Pentax WG-1 GPS's 2.7" screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.