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 D3 and Nikon P310 side-by-side from the front, back and top in their relative dimensions. Nikon D3 has external dimensions of 160 x 157 x 88 mm (6.3 x 6.18 x 3.46″) and weighs 1300 g (2.87 lb / 45.86 oz) (including batteries). Nikon P310 has external dimensions of 103 x 58 x 32 mm (4.06 x 2.28 x 1.26″) and weighs 194 g (0.43 lb / 6.84 oz) (including batteries).
Below you can see the front-view size comparison of the Nikon D3 and the Nikon P310. Nikon P310 is clearly the smaller of the two cameras. Its body is 57mm narrower, 99mm shorter and 56mm thinner than Nikon D3. As you can tell, actually this is not a fair size comparison since Nikon P310 has a built-in lens but Nikon D3 doesn't. Once you put a lens on D3, its thickness will increase significantly.
Here is the back view size comparison of the Nikon D3 and Nikon P310.
Now lets look at the top view comparison of Nikon D3 and Nikon P310.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Nikon P310 is significantly lighter (1106g ) than the Nikon D3 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 D3, the total kit will weigh much higher.
Weather Sealing
With its weather-sealed body, we believe that the D3 has a big advantage over the P310 which doesn't provide any kind of environmental sealing.
LCD Screen Size and Features
Nikon D3 and Nikon P310's LCD screens have the same diagonal size of 3.00 inches.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.