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 D3100 and Nikon L830 side-by-side from the front, back and top in their relative dimensions. Nikon D3100 has external dimensions of 124 x 96 x 75 mm (4.88 x 3.78 x 2.95″) and weighs 505 g (1.11 lb / 17.81 oz) (including batteries). Nikon L830 has external dimensions of 110 x 76 x 91 mm (4.33 x 2.99 x 3.58″) and weighs 508 g (1.12 lb / 17.92 oz) (including batteries).
Below you can see the front-view size comparison of the Nikon D3100 and the Nikon L830. Nikon L830 is 14mm narrower and 20mm shorter than Nikon D3100 but it is also 16mm thicker. As you can tell, actually this is not a fair size comparison since Nikon L830 has a built-in lens but Nikon D3100 doesn't. Once you put a lens on D3100, its thickness will increase significantly.
Here is the back view size comparison of the Nikon D3100 and Nikon L830.
Now lets look at the top view comparison of Nikon D3100 and Nikon L830.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Nikon D3100 is 3g lighter than the Nikon L830 but we don't think this will make a significant difference.
Again, this comparison may not be very useful in real life as we are comparing the weight of a camera with a built-in lens to the body-only weight of an interchangeable lens camera. Once you put a lens on D3100, the total kit will weigh much higher.
Weather Sealing
Unfortunately neither the Nikon D3100 nor Nikon Coolpix L830 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 Top Bridge Cameras with Weather Sealing
LCD Screen Size and Features
Nikon D3100 and Nikon L830's LCD screens have the same diagonal size of 3.00 inches.
On the other hand, Nikon L830 features a
Tilting screen where you can change the angle of the screen to make it easier to shoot from waist or over-the-head levels whereas the Nikon D3100 has a fixed type screen which provides less flexibility in shooting positions compared to L830.