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 FX48 and Pentax K-r side-by-side from the front, back and top in their relative dimensions. Panasonic FX48 has external dimensions of 95 x 53 x 22 mm (3.74 x 2.09 x 0.87″) and weighs 150 g (0.33 lb / 5.29 oz) (including batteries). Pentax K-r has external dimensions of 125 x 97 x 68 mm (4.92 x 3.82 x 2.68″) and weighs 598 g (1.32 lb / 21.09 oz) (including batteries).
Below you can see the front view size comparison of Panasonic FX48 and Pentax K-r. Panasonic FX48 is clearly the smaller of the two cameras. Its body is 30mm narrower, 44mm shorter and 46mm thinner than Pentax K-r. As you can tell, actually this is not a fair size comparison since Panasonic FX48 has a built-in lens but Pentax K-r doesn't. Once you put a lens on K-r, its thickness will increase significantly.
Here is the back view size comparison of Panasonic FX48 and Pentax K-r.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Panasonic FX48 is significantly lighter (448g ) than the Pentax K-r 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 K-r, the total kit will weigh much higher.
Unfortunately neither Panasonic Lumix DMC-FX48 (Lumix DMC-FX40) nor Pentax K-r 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 DSLR Cameras with Weather Sealing
LCD Screen Size and Features
Pentax K-r's 3" LCD screen is slightly larger than Panasonic FX48's 2.5" screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.