In a method for 3D radius correction in CNC milling, a mill path of an original milling tool producing a surface contour on a workpiece is calculated for an original milling tool based on dimensions of the mill cutter tip, with the positions of the mill cutter tip specified by an NC program. A surface normal of an end face milling surface and a surface normal of a circumferential milling surface are then specified, for each position of the mill cutter tip taking into account dimensional differences between an actually available milling tool and the original milling tool. By specifying along the mill path a spatial orientation of the milling tool axis, a correction vector is specified from the milling tool orientation, dimensional differences and the surface normals, and the workpiece is machined by traversing the mill path with the actual milling tool under consideration of the correction vector.