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 Canon T8i and Sony A58 side-by-side from the front, back and top in their relative dimensions. Canon T8i has external dimensions of 131 x 103 x 76 mm (5.16 x 4.00 x 2.99″) and weighs 515 g (1.14 lb / 18.17 oz) (including batteries). Sony A58 has external dimensions of 129 x 95 x 78 mm (5.08 x 3.74 x 3.07″) and weighs 492 g (1.08 lb / 17.35 oz) (including batteries).
Below you can see the front-view size comparison of the Canon T8i and the Sony A58. Sony A58 is 2mm narrower and 8mm shorter than Canon T8i but it is also 2mm thicker.
Here is the back view size comparison of the Canon T8i and Sony A58.
Now lets look at the top view comparison of Canon T8i and Sony A58.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Sony A58 is 23g lighter than the Canon T8i 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 Canon T8i and Sony A58 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 Canon EOS Rebel T8i (EOS 850D / EOS Kiss X10i) nor Sony SLT-A58 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
Canon T8i's 3.00" LCD screen is slightly larger than Sony A58's 2.7" screen.