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 Sony A850 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). Sony A850 has external dimensions of 156 x 117 x 82 mm (6.14 x 4.61 x 3.23″) and weighs 895 g (1.97 lb / 31.57 oz) (including batteries).
Below you can see the front view size comparison of Canon G1 X III and Sony A850. Canon G1 X III is clearly the smaller of the two cameras. Its body is 41mm narrower, 39mm shorter and 31mm thinner than Sony A850. As you can tell, actually this is not a fair size comparison since Canon G1 X III has a built-in lens but Sony A850 doesn't. Once you put a lens on A850, its thickness will increase significantly.
Here is the back view size comparison of Canon G1 X III and Sony A850.
Now lets look at the top view comparison of Canon G1 X III and Sony A850.
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 (496g ) than the Sony A850 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 A850, the total kit will weigh much higher.
Both G1 X III and A850 have weather sealings in their body, making them resistant to water and dust.
LCD Screen Size and Features
Canon G1 X III and Sony A850's LCD screens has the same diagonal size of 3".
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. Sony A850's LCD screen is a fixed type which provides almost no flexibility in shooting positions compared to G1 X III.