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 D100 and Nikon D40 side-by-side from the front, back and top in their relative dimensions. Nikon D100 has external dimensions of 144 x 116 x 81 mm (5.67 x 4.57 x 3.19″) and weighs 780 g (1.72 lb / 27.51 oz) (including batteries). Nikon D40 has external dimensions of 124 x 94 x 64 mm (4.88 x 3.7 x 2.52″) and weighs 522 g (1.15 lb / 18.41 oz) (including batteries).
Below you can see the front-view size comparison of the Nikon D100 and the Nikon D40. Nikon D40 is clearly the smaller of the two cameras. Its body is 20mm narrower, 22mm shorter and 17mm thinner than Nikon D100.
Comparison image of the Nikon D100 and the Nikon D40 Size, Weight and External Dimensions - Front View
Now lets look at the top view comparison of Nikon D100 and Nikon D40.
Top View Comparison image of the Nikon D100 and the Nikon D40 Size
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Nikon D40 is significantly lighter (258g ) than the Nikon D100 which may become a big advantage especially on long walking trips.
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 Nikon D100 and Nikon D40 have the same Nikon F lens mount and APS-C sized sensors, lenses will not be a differentiator on total size of the system.
Weather Sealing
Unfortunately neither the Nikon D100 nor Nikon D40 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
Nikon D40's 2.50" LCD screen is slightly larger than Nikon D100's 1.8 screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.
