Below you can see the front view size comparison of Nikon D3300 and Nikon D5200. Nikon D3300 is 5mm narrower and 2mm thinner than Nikon D3300 but they have the same height of 98mm.
Nikon D3300 vs Nikon D5200 - Front View
Nikon D3300 vs Nikon D5200 - 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