Size and weight is a big decision factor when you are trying to find the ideal camera for your needs.
In this section, We are going to illustrate Nikon D3400 and Sony QX1 side-by-side from the front, back and top in their relative dimensions. Nikon D3400 has external dimensions of 124 x 98 x 76 mm (4.88 x 3.86 x 2.99″) and weighs 395 g (0.87 lb / 13.93 oz) (including batteries). Sony QX1 has external dimensions of 74 x 70 x 53 mm (2.91 x 2.76 x 2.09″) and weighs 216 g (0.48 lb / 7.62 oz) (including batteries).
Below you can see the front view size comparison of Nikon D3400 and Sony QX1. Sony QX1 is clearly the smaller of the two cameras. Its body is 50mm narrower, 28mm shorter and 23mm thinner than Nikon D3400.
Here is the back view size comparison of Nikon D3400 and Sony QX1.
Now lets look at the top view comparison of Nikon D3400 and Sony QX1.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Sony QX1 is significantly lighter (179g ) than the Nikon D3400 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 have to also take into account the lenses that you will be using with these bodies. Since both Nikon D3400 and Sony QX1 have the same APS-C sized sensor, their lenses for a similar focal length and aperture will be similar in size and weight.
Unfortunately neither Nikon D3400 nor Sony Alpha QX1 provides any type of weather sealing in their body, 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 DSLR Cameras with Weather Sealing Top Compact Cameras with Weather Sealing
LCD Screen Size and Features
Nikon D3400's 3.00" LCD screen is slightly larger than Sony QX1's screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.