The size of the WD My Passport depends on which capacity that you get. The WD My Passport Ultra 1TB drive that we are looking at today measures in at 110.5mm x 82mm x 15.4mm with a weight of 5.44 ounces. Western Digital is using a 1TB WD Blue 5400 RPM hard drive with two platters and a 7mm Z-height on this particular drive. Flipping the My Passport Ultra over we see that WD placed four rubber pads on the bottom to keep the portable hard drive from sliding around the surface that you place it on.