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 Pentax WG-3 and Panasonic GM5 side-by-side from the front, back and top in their relative dimensions. Pentax WG-3 has external dimensions of 124 x 64 x 33 mm (4.9 x 2.5 x 1.3″) and weighs 230 g (0.51 lb / 8.11 oz) (including batteries). Panasonic GM5 has external dimensions of 99 x 60 x 36 mm (3.9 x 2.36 x 1.42″) and weighs 211 g (0.47 lb / 7.44 oz) (including batteries).
Below you can see the front-view size comparison of the Pentax WG-3 and the Panasonic GM5. Panasonic GM5 is 25mm narrower and 4mm shorter than Pentax WG-3 but it is also 3mm thicker. As you can tell, actually this is not a fair size comparison since Pentax WG-3 has a built-in lens but Panasonic GM5 doesn't. Once you put a lens on GM5, its thickness will increase significantly.
Here is the back view size comparison of the Pentax WG-3 and Panasonic GM5.
Now lets look at the top view comparison of Pentax WG-3 and Panasonic GM5.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Panasonic GM5 is 19g lighter than the Pentax WG-3 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 GM5, the total kit will weigh much higher.
Weather Sealing
Thanks to the weather-sealed body of the WG-3, you can use this camera with more confidence under conditions where there is risk of exposure to water and dust compared to the GM5.
LCD Screen Size and Features
Pentax WG-3 and Panasonic GM5's LCD screens have the same diagonal size of 3.00 inches.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.