Disclosed is a method implemented by computer for determining a lens blank intended to be used for the manufacturing of a finished optical article. The method includes: —a virtual volume data determining step, during which virtual volume data are determined based at least on finished optical article data representative of the volume of the finished optical article and over-thickness data representative of over-thickness requirements, the virtual volume data are determined so that the virtual volume defined by the virtual volume data includes the volume of the finished optical article volume of the finished optical article and the over-thickness, —a lens blank determining step, during which a lens blank is determined based on the virtual volume data so as to include the virtual volume defined by the virtual volume data.