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 Casio EX-100 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). Casio EX-100 has external dimensions of 119x67x50 mm and weighs 389 g (including batteries).
Below you can see the front-view size comparison of the Olympus E-M10 III and the Casio EX-100. Casio EX-100 is 3mm narrower and 17mm shorter than Olympus E-M10 III but they have the same thickness of 50mm. As you can tell, actually this is not a fair size comparison since Casio EX-100 has a built-in lens but Olympus E-M10 III doesn't. Once you put a lens on E-M10 III, its thickness will increase significantly.
Here is the back view size comparison of the Olympus E-M10 III and Casio EX-100.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Casio EX-100 is 21g lighter than the Olympus E-M10 III 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 E-M10 III, the total kit will weigh much higher.
Weather Sealing
Unfortunately neither the Olympus OM-D E-M10 Mark III nor Casio Exilim EX-100 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 Top Compact Cameras with Weather Sealing
LCD Screen Size and Features
Casio EX-100's 3.50" LCD screen is slightly larger than Olympus E-M10 III's 3 screen.