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 Canon SL3 and Nikon D3300 side-by-side from the front, back and top in their relative dimensions. 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). Nikon D3300 has external dimensions of 124 x 98 x 76 mm (4.88 x 3.86 x 2.99″) and weighs 430 g (0.95 lb / 15.17 oz) (including batteries).
Below you can see the front view size comparison of Canon SL3 and Nikon D3300. Canon SL3 is clearly the smaller of the two cameras. Its body is 2mm narrower, 5mm shorter and 6mm thinner than Nikon D3300.
Here is the back view size comparison of Canon SL3 and Nikon D3300.
Now lets look at the top view comparison of Canon SL3 and Nikon D3300.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Nikon D3300 is 19g 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 have to also take into account the lenses that you will be using with these bodies. Since both Canon SL3 and Nikon D3300 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 Canon EOS Rebel SL3 (EOS 250D / EOS Kiss X10) nor Nikon D3300 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
LCD Screen Size and Features
Canon SL3 and Nikon D3300's LCD screens has the same diagonal size of 3.00".
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 D3300's LCD screen is a fixed type which provides almost no flexibility in shooting positions compared to SL3.