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 Nikon L31 and Nikon S3100 side-by-side from the front, back and top in their relative dimensions. Nikon L31 has external dimensions of 96 x 59 x 29 mm (3.78 x 2.32 x 1.14″) and weighs 160 g (0.35 lb / 5.64 oz) (including batteries). Nikon S3100 has external dimensions of 94 x 58 x 18 mm (3.7 x 2.28 x 0.71″) and weighs 118 g (0.26 lb / 4.16 oz) (including batteries).
Below you can see the front view size comparison of Nikon L31 and Nikon S3100. Nikon S3100 is clearly the smaller of the two cameras. Its body is 2mm narrower, 1mm shorter and 11mm thinner than Nikon L31.
Here is the back view size comparison of Nikon L31 and Nikon S3100.
Now lets look at the top view comparison of Nikon L31 and Nikon S3100.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Nikon S3100 is significantly lighter (42g ) than the Nikon L31 which may become a big advantage especially on long walking trips.
Unfortunately neither Nikon Coolpix L31 nor Nikon Coolpix S3100 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 Compact Cameras with Weather Sealing
LCD Screen Size and Features
Nikon L31 and Nikon S3100's LCD screens has the same diagonal size of 2.70".
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.