Below you can see the front view size comparison of Nikon 1 J3 and Nikon Z6. Nikon 1 J3 is clearly the smaller of the two cameras. Its body is 33mm narrower, 40mm shorter and 39mm thinner than Nikon Z6.
Nikon 1 J3 vs Nikon Z6 - Front View
Nikon 1 J3 vs Nikon Z6 - Top View
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.
Camera Size Comparison
Select Two Cameras for Size Comparison