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 Nikon D3400 and Canon SL3 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). Canon SL3 has external dimensions of 122 x 93 x 70 mm (4.8 x 3.66 x 2.76″) and weighs 449 g (0.99 lb / 15.84 oz) (including batteries).
Below you can see the front-view size comparison of the Nikon D3400 and the Canon SL3. Canon SL3 is clearly the smaller of the two cameras. Its body is 2mm narrower, 5mm shorter and 6mm thinner than Nikon D3400.
Here is the back view size comparison of the Nikon D3400 and Canon SL3.
Now lets look at the top view comparison of Nikon D3400 and Canon SL3.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Nikon D3400 is 54g lighter than the Canon SL3 but we don't think this will make a significant difference.
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 Nikon D3400 and Canon SL3 have the same APS-C sized sensor, their lenses for a similar focal length and aperture will be similar in size and weight.
Weather Sealing
Unfortunately neither the Nikon D3400 nor Canon EOS Rebel SL3 (EOS 250D / EOS Kiss X10) 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 DSLR Cameras with Weather Sealing
LCD Screen Size and Features
Nikon D3400 and Canon SL3's LCD screens have the same diagonal size of 3.00 inches.
On the other hand, Canon SL3 sports a
Fully Articulated screen which you can change the angle and position of the screen almost freely, making it possible to shoot from waist or over-the-head levels, and especially very useful for shooting selfies and video. Nikon D3400's LCD screen is a fixed type which provides almost no flexibility in shooting positions compared to SL3.