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 Casio EX-Z400 and Panasonic G1 side-by-side from the front, back and top in their relative dimensions. Casio EX-Z400 has external dimensions of 95 x 60 x 23 mm (3.74 x 2.36 x 0.91″) and weighs 130 g (0.29 lb / 4.59 oz) (including batteries). Panasonic G1 has external dimensions of 124 x 84 x 45 mm (4.88 x 3.31 x 1.77″) and weighs 360 g (0.79 lb / 12.70 oz) (including batteries).
Below you can see the front-view size comparison of the Casio EX-Z400 and the Panasonic G1. Casio EX-Z400 is clearly the smaller of the two cameras. Its body is 29mm narrower, 24mm shorter and 22mm thinner than Panasonic G1. As you can tell, actually this is not a fair size comparison since Casio EX-Z400 has a built-in lens but Panasonic G1 doesn't. Once you put a lens on G1, its thickness will increase significantly.
Here is the back view size comparison of the Casio EX-Z400 and Panasonic G1.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Casio EX-Z400 is significantly lighter (230g ) than the Panasonic G1 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 G1, the total kit will weigh much higher.
Weather Sealing
Unfortunately neither the Casio Exilim EX-Z400 nor Panasonic Lumix DMC-G1 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
Casio EX-Z400 and Panasonic G1's LCD screens have the same diagonal size of 3.00 inches.
On the other hand, Panasonic G1 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. Casio EX-Z400's LCD screen is a fixed type which provides almost no flexibility in shooting positions compared to G1.