Below you can see the front view size comparison of Olympus E-PM1 and Panasonic G9. Olympus E-PM1 is clearly the smaller of the two cameras. Its body is 27mm narrower, 33mm shorter and 58mm thinner than Panasonic G9.
Olympus E-PM1 vs Panasonic G9 - Front View
Olympus E-PM1 vs Panasonic G9 - 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