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 D7100 and Nikon S3700 side-by-side from the front, back and top in their relative dimensions. Nikon D7100 has external dimensions of 136 x 107 x 76 mm (5.35 x 4.21 x 2.99″) and weighs 765 g (1.69 lb / 26.98 oz) (including batteries). Nikon S3700 has external dimensions of 96 x 58 x 20 mm (3.78 x 2.28 x 0.79″) and weighs 118 g (0.26 lb / 4.16 oz) (including batteries).
Below you can see the front-view size comparison of the Nikon D7100 and the Nikon S3700. Nikon S3700 is clearly the smaller of the two cameras. Its body is 40mm narrower, 49mm shorter and 56mm thinner than Nikon D7100. As you can tell, actually this is not a fair size comparison since Nikon S3700 has a built-in lens but Nikon D7100 doesn't. Once you put a lens on D7100, its thickness will increase significantly.
Here is the back view size comparison of the Nikon D7100 and Nikon S3700.
Now lets look at the top view comparison of Nikon D7100 and Nikon S3700.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Nikon S3700 is significantly lighter (647g ) than the Nikon D7100 which may become a big advantage especially on long walking trips.
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 D7100, the total kit will weigh much higher.
Weather Sealing
With its weather-sealed body, we believe that the D7100 has a big advantage over the S3700 which doesn't provide any kind of environmental sealing.
LCD Screen Size and Features
Nikon D7100's 3.20" LCD screen is slightly larger than Nikon S3700's 2.7 screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.