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 Panasonic ZS3 and Nikon 1 J3 side-by-side from the front, back and top in their relative dimensions. Panasonic ZS3 has external dimensions of 103 x 60 x 33 mm (4.06 x 2.36 x 1.3″) and weighs 229 g (0.50 lb / 8.08 oz) (including batteries). Nikon 1 J3 has external dimensions of 101 x 61 x 29 mm (3.98 x 2.4 x 1.14″) and weighs 201 g (0.44 lb / 7.09 oz) (including batteries).
Below you can see the front view size comparison of Panasonic ZS3 and Nikon 1 J3. Nikon 1 J3 is 2mm narrower and 4mm thinner than Panasonic ZS3 but it is also 1mm taller. As you can tell, actually this is not a fair size comparison since Panasonic ZS3 has a built-in lens but Nikon 1 J3 doesn't. Once you put a lens on 1 J3, its thickness will increase significantly.
Now lets look at the top view comparison of Panasonic ZS3 and Nikon 1 J3.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Nikon 1 J3 is 28g lighter than the Panasonic ZS3 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 1 J3, the total kit will weigh much higher.
Unfortunately neither Panasonic Lumix DMC-ZS3 (Lumix DMC-TZ7) nor Nikon 1 J3 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 Top Mirrorless Cameras with Weather Sealing
LCD Screen Size and Features
Panasonic ZS3 and Nikon 1 J3's LCD screens has the same diagonal size of 3".
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.