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 G12 and Pentax Q side-by-side from the front, back and top in their relative dimensions. Canon G12 has external dimensions of 112 x 76 x 48 mm (4.41 x 2.99 x 1.89″) and weighs 401 g (0.88 lb / 14.14 oz) (including batteries). Pentax Q has external dimensions of 98 x 57 x 31 mm (3.86 x 2.24 x 1.22″) and weighs 180 g (0.40 lb / 6.35 oz) (including batteries).
Below you can see the front view size comparison of Canon G12 and Pentax Q. Pentax Q is clearly the smaller of the two cameras. Its body is 14mm narrower, 19mm shorter and 17mm thinner than Canon G12. As you can tell, actually this is not a fair size comparison since Canon G12 has a built-in lens but Pentax Q doesn't. Once you put a lens on Q, its thickness will increase significantly.
Here is the back view size comparison of Canon G12 and Pentax Q.
Now lets look at the top view comparison of Canon G12 and Pentax Q.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Pentax Q is significantly lighter (221g ) than the Canon G12 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 Q, the total kit will weigh much higher.
Unfortunately neither Canon PowerShot G12 nor Pentax Q provides any type of weather sealing in their body, so you have to give extra care especially when you are shooting outdoors. If weather sealing is a must-have feature for you, check these sections: Top Compact Cameras with Weather Sealing Top Mirrorless Cameras with Weather Sealing
LCD Screen Size and Features
Pentax Q's 3" LCD screen is slightly larger than Canon G12's 2.8" screen.
On the other hand, Canon G12 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 Q has a fixed type screen which provides almost no flexibility in shooting positions compared to G12.