Below you can see the front view size comparison of Canon G16 and Panasonic ZR3. Panasonic ZR3 is clearly the smaller of the two cameras. Its body is 11mm narrower, 21mm shorter and 14mm thinner than Canon G16.
Canon G16 vs Panasonic ZR3 - Front View
Canon G16 vs Panasonic ZR3 - 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