Below you can see the front-view size comparison of the Nikon 1 J3 and Panasonic S1R. The Nikon 1 J3 is clearly the smaller of the two cameras. Its body is 48mm narrower, 49 mm shorter and 68 mm thinner than the Panasonic S1R.
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.