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 Panasonic FZ100 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). Panasonic FZ100 has external dimensions of 124 x 82 x 92 mm (4.88 x 3.23 x 3.62″) and weighs 540 g (1.19 lb / 19.05 oz) (including batteries).
Below you can see the front view size comparison of Panasonic ZS3 and Panasonic FZ100. Panasonic ZS3 is clearly the smaller of the two cameras. Its body is 21mm narrower, 22mm shorter and 59mm thinner than Panasonic FZ100.
Here is the back view size comparison of Panasonic ZS3 and Panasonic FZ100.
Now lets look at the top view comparison of Panasonic ZS3 and Panasonic FZ100.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Panasonic ZS3 is significantly lighter (311g ) than the Panasonic FZ100 which may become a big advantage especially on long walking trips.
Unfortunately neither Panasonic Lumix DMC-ZS3 (Lumix DMC-TZ7) nor Panasonic Lumix DMC-FZ100 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 Bridge Cameras with Weather Sealing
LCD Screen Size and Features
Panasonic ZS3 and Panasonic FZ100's LCD screens has the same diagonal size of 3".
On the other hand, Panasonic FZ100 sports a Fully Articulated screen
which you can change the angle and position of the screen almost freely, making it possible to shoot from waist or over the head levels, and especially very useful for shooting selfies and video. Panasonic ZS3's LCD screen is a fixed type which provides almost no flexibility in shooting positions compared to FZ100.