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 Olympus E-M10 III and Panasonic GM1 side-by-side from the front, back and top in their relative dimensions. Olympus E-M10 III has external dimensions of 122 x 84 x 50 mm (4.8 x 3.31 x 1.97″) and weighs 410 g (0.90 lb / 14.46 oz) (including batteries). Panasonic GM1 has external dimensions of 99 x 55 x 30 mm (3.88 x 2.16 x 1.2″) and weighs 204 g (0.45 lb / 7.20 oz) (including batteries).
Below you can see the front-view size comparison of the Olympus E-M10 III and the Panasonic GM1. Panasonic GM1 is clearly the smaller of the two cameras. Its body is 23mm narrower, 29mm shorter and 20mm thinner than Olympus E-M10 III.
Here is the back view size comparison of the Olympus E-M10 III and Panasonic GM1.
Now lets look at the top view comparison of Olympus E-M10 III and Panasonic GM1.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Panasonic GM1 is significantly lighter (206g ) than the Olympus E-M10 III which may become a big advantage especially on long walking trips.
Also keep in mind that body weight is not the only deciding factor when comparing two interchangeable camera bodies, you also have to take into account the lenses that you will be using with these bodies. Since both Olympus E-M10 III and Panasonic GM1 have the same Micro Four Thirds lens mount and Four Thirds sized sensors, lenses will not be a differentiator on total size of the system.
Weather Sealing
Unfortunately neither the Olympus OM-D E-M10 Mark III nor Panasonic Lumix DMC-GM1 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 Mirrorless Cameras with Weather Sealing
LCD Screen Size and Features
Olympus E-M10 III and Panasonic GM1's LCD screens have the same diagonal size of 3.00 inches.
On the other hand, Olympus E-M10 III features a
Tilting screen where you can change the angle of the screen to make it easier to shoot from waist or over-the-head levels whereas the Panasonic GM1 has a fixed type screen which provides less flexibility in shooting positions compared to E-M10 III.