This paper addresses the design of aerostatic bearings for use within machines requiring nanometre precise translation or rotation. The major design parameters which affect aerostatic bearing performance are discussed. The supply pressure ratio and hence, the bearing clearance and the type and specific size of inlet flow control device are shown to require special consideration. Specific information on the tolerance of each of the parameters which have a direct effect on the nano-precision location of these bearings is given. In addition the paper addresses the manufacturing tolerances and manufacturing variations which can occur in practice and places limits on the magnitude that these sources of errors can contribute to the permissible manufacturing variations.