This work studies the characteristics of the aerodynamics design of a box wing aircraft (BWA) with the potential gain of aerodynamics efficiency. The first objective of this paper is to study how BWA planform geometric parameters affect the aerodynamics efficiency. This is carried out using literature data and vortex lattice program. The second objective is to compare aerodynamics efficiency between BWA and conventional mid-range market aircraft. These comparisons are done considering trimming, Reynolds number variation and two types of airfoils.