Below you can see the front view size comparison of Panasonic GX8 and Nikon D7500. Panasonic GX8 is clearly the smaller of the two cameras. Its body is 3mm narrower, 26mm shorter and 10mm thinner than Nikon D7500.
Panasonic GX8 vs Nikon D7500 - Front View
Panasonic GX8 vs Nikon D7500 - 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