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 Sony G3 and Pentax Q-S1 side-by-side from the front, back and top in their relative dimensions. Sony G3 has external dimensions of 97 x 59 x 22 mm (3.82 x 2.32 x 0.87″) and weighs 185 g (0.41 lb / 6.53 oz) (including batteries). Pentax Q-S1 has external dimensions of 105 x 58 x 34 mm (4.13 x 2.28 x 1.34″) and weighs 203 g (0.45 lb / 7.16 oz) (including batteries).
Below you can see the front-view size comparison of the Sony G3 and the Pentax Q-S1. Sony G3 is 8mm narrower and 12mm thinner than Pentax Q-S1 but it is also 1mm taller. As you can tell, actually this is not a fair size comparison since Sony G3 has a built-in lens but Pentax Q-S1 doesn't. Once you put a lens on Q-S1, its thickness will increase significantly.
Here is the back view size comparison of the Sony G3 and Pentax Q-S1.
Now lets look at the top view comparison of Sony G3 and Pentax Q-S1.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Sony G3 is 18g lighter than the Pentax Q-S1 but we don't think this will make a significant difference.
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-S1, the total kit will weigh much higher.
Weather Sealing
Unfortunately neither the Sony Cyber-shot DSC-G3 nor Pentax Q-S1 provides any type of weather sealing in their bodies, 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
Sony G3's 3.50" LCD screen is slightly larger than Pentax Q-S1's 3 screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.