Size and weight is a big decision factor when you are trying to find the ideal camera for your needs.
In this section, We are going to illustrate Canon G1 X III and Pentax K-3 II side-by-side from the front, back and top in their relative dimensions. Canon G1 X III has external dimensions of 115 x 78 x 51 mm (4.53 x 3.07 x 2.01″) and weighs 399 g (0.88 lb / 14.07 oz) (including batteries). Pentax K-3 II has external dimensions of 131 x 100 x 77 mm (5.16 x 3.94 x 3.03″) and weighs 800 g (1.76 lb / 28.22 oz) (including batteries).
Below you can see the front view size comparison of Canon G1 X III and Pentax K-3 II. Canon G1 X III is clearly the smaller of the two cameras. Its body is 16mm narrower, 22mm shorter and 26mm thinner than Pentax K-3 II. As you can tell, actually this is not a fair size comparison since Canon G1 X III has a built-in lens but Pentax K-3 II doesn't. Once you put a lens on K-3 II, its thickness will increase significantly.
Here is the back view size comparison of Canon G1 X III and Pentax K-3 II.
Now lets look at the top view comparison of Canon G1 X III and Pentax K-3 II.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Canon G1 X III is significantly lighter (401g ) than the Pentax K-3 II 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 K-3 II, the total kit will weigh much higher.
Both G1 X III and K-3 II have weather sealings in their body, making them resistant to water and dust.
LCD Screen Size and Features
Pentax K-3 II's 3.2 LCD screen is slightly larger than Canon G1 X III's 3" screen.
On the other hand, Canon G1 X III sports a Fully Articulated screen
which you can change the angle and position of the screen almost freely, making it possible to shoot from waist or over the head levels, and especially very useful for shooting selfies and video. On the other hand, Pentax K-3 II has a fixed type screen which provides almost no flexibility in shooting positions compared to G1 X III.