The air breathing propulsion system used for hypersonic vehicle cruising is a scramjet. Inlet design is one of the important step in overall design of scramjet. The initial steps in the inlet design process consist of identification of shock angles, shock hitting points and there after evaluation of performance parameters using inviscid flow consideration at a given Mach number called design Mach number. During the flight, the vehicle operates on the off-design conditions. The current study focusses on the effect of these off-design conditions such as variation of freestream Mach number, angle of attack, total temperature on the flow field and performance parameters using inviscid flow assumption. The performance parameters considered in the present study are total pressure recovery, static pressure ratio, static temperature ratio, kinetic energy efficiency, adiabatic compression efficiency, non-dimensional entropy increase.