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 Sony HX400V and Sony a5100 side-by-side from the front, back and top in their relative dimensions. Sony HX400V has external dimensions of 130 x 93 x 103 mm (5.1 x 3.67 x 4.06″) and weighs 660 g (1.46 lb / 23.28 oz) (including batteries). Sony a5100 has external dimensions of 110 x 63 x 36 mm (4.33 x 2.48 x 1.42″) and weighs 283 g (0.62 lb / 9.98 oz) (including batteries).
Below you can see the front-view size comparison of the Sony HX400V and the Sony a5100. Sony a5100 is clearly the smaller of the two cameras. Its body is 20mm narrower, 30mm shorter and 67mm thinner than Sony HX400V. As you can tell, actually this is not a fair size comparison since Sony HX400V has a built-in lens but Sony a5100 doesn't. Once you put a lens on a5100, its thickness will increase significantly.
Here is the back view size comparison of the Sony HX400V and Sony a5100.
Now lets look at the top view comparison of Sony HX400V and Sony a5100.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Sony a5100 is significantly lighter (377g ) than the Sony HX400V 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 a5100, the total kit will weigh much higher.
Weather Sealing
Unfortunately neither the Sony Cyber-shot DSC-HX400V nor Sony Alpha a5100 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 Bridge Cameras with Weather Sealing Top Mirrorless Cameras with Weather Sealing
LCD Screen Size and Features
Sony HX400V and Sony a5100's LCD screens have the same diagonal size of 3.00 inches.
Both cameras feature
Tilting screens where you can change the angle of the screen to make it easier to shoot from waist or over-the-head levels.