Method for the optimization of the surface geometry or of a variable, dependent on this, or variables, dependent on this, of bevel or hypoid gears for their production on a free-form machine which can be mapped to a free-form basic machine with at most six axes uniquely in a reversible way, even to symmetries, which has a gearwheel to be machined and a tool which are in each case rotatable about an axis, and the tool and the gearwheel to be machined are moveable, preferably displaceable or rotatable, with respect to one another along or about a plurality of axes, the optimization of the surface geometry or of the variable or variables, dependent on this, of the bevel or hypoid gearwheel taking place in that one or more control parameters, which has or have influence on the surface geometry or the variable or variables, dependent on this, of the bevel or hypoid gearwheel, is or are varied by means of a simulation of the gearwheel production process and/or a roll and/or a load-contact analysis on the free-form basic machine, until the surface geometry or the variable or variables, dependent on this, of the bevel or hypoid gearwheel thereby corresponds at least to a predetermined target value.