Below you can see the front-view size comparison of the Nikon 1 J3 and Panasonic GX85. The Nikon 1 J3 is clearly the smaller of the two cameras. Its body is 21mm narrower, 10 mm shorter and 15 mm thinner than the Panasonic GX85.
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.