Below you can see the front view size comparison of Olympus E-PL9 and Panasonic GM1. Panasonic GM1 is clearly the smaller of the two cameras. Its body is 18mm narrower, 13mm shorter and 9mm thinner than Olympus E-PL9.
Olympus E-PL9 vs Panasonic GM1 - Front View
Olympus E-PL9 vs Panasonic GM1 - 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