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 T7i and Canon T6i side-by-side from the front, back and top in their relative dimensions. Canon T7i has external dimensions of 131 x 100 x 76 mm (5.16 x 3.94 x 2.99″) and weighs 532 g (1.17 lb / 18.77 oz) (including batteries). Canon T6i has external dimensions of 132 x 101 x 78 mm (5.2 x 3.98 x 3.07″) and weighs 555 g (1.22 lb / 19.58 oz) (including batteries).
Below you can see the front view size comparison of Canon T7i and Canon T6i. Canon T7i is clearly the smaller of the two cameras. Its body is 1mm narrower, 1mm shorter and 2mm thinner than Canon T6i.
Here is the back view size comparison of Canon T7i and Canon T6i.
Now lets look at the top view comparison of Canon T7i and Canon T6i.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Canon T7i is 23g lighter than the Canon T6i 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 T7i and Canon T6i have the same Canon EF/EF-S lens mount and APS-C sized sensors, lenses will not be a differentiator on total size of the system.
Unfortunately neither Canon EOS Rebel T7i / EOS 800D / Kiss X9i nor Canon EOS Rebel T6i (EOS 750D / Kiss X8i) 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 T7i and Canon T6i's LCD screens has the same diagonal size of 3".
Both cameras feature Fully Articulating screens
where you can change the angle of the screen to make it easier to shoot from waist or over the head levels. Fully articulating screens are also useful for taking Selfie shots and video.