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 RZ18 and Canon 500D side-by-side from the front, back and top in their relative dimensions. Pentax RZ18 has external dimensions of 97 x 61 x 33 mm (3.82 x 2.4 x 1.3″) and weighs 178 g (0.39 lb / 6.28 oz) (including batteries). Canon 500D has external dimensions of 129 x 98 x 62 mm (5.08 x 3.86 x 2.44″) and weighs 520 g (1.15 lb / 18.34 oz) (including batteries).
Below you can see the front-view size comparison of the Pentax RZ18 and the Canon 500D. Pentax RZ18 is clearly the smaller of the two cameras. Its body is 32mm narrower, 37mm shorter and 29mm thinner than Canon 500D. As you can tell, actually this is not a fair size comparison since Pentax RZ18 has a built-in lens but Canon 500D doesn't. Once you put a lens on 500D, its thickness will increase significantly.
Here is the back view size comparison of the Pentax RZ18 and Canon 500D.
Now lets look at the top view comparison of Pentax RZ18 and Canon 500D.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Pentax RZ18 is significantly lighter (342g ) than the Canon 500D 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 500D, the total kit will weigh much higher.
Weather Sealing
With its weather-sealed body, we believe that the RZ18 has a big advantage over the 500D which doesn't provide any kind of environmental sealing.
LCD Screen Size and Features
Pentax RZ18 and Canon 500D's LCD screens have the same diagonal size of 3.00 inches.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.