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 Canon SX150 IS 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). Canon SX150 IS has external dimensions of 113 x 73 x 46 mm (4.45 x 2.87 x 1.81″) and weighs 306 g (0.67 lb / 10.79 oz) (including batteries).
Below you can see the front view size comparison of Canon G12 and Canon SX150 IS. Canon SX150 IS is 3mm shorter and 2mm thinner than Canon G12 but it is also 1mm wider.
Now lets look at the top view comparison of Canon G12 and Canon SX150 IS.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Canon SX150 IS is significantly lighter (95g ) than the Canon G12 which may become a big advantage especially on long walking trips.
Unfortunately neither Canon PowerShot G12 nor Canon PowerShot SX150 IS 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
LCD Screen Size and Features
Canon SX150 IS'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, Canon SX150 IS has a fixed type screen which provides almost no flexibility in shooting positions compared to G12.