A method for auto-calibration of at least one tool (36) in a single point turning machine (10) used for manufacturing in particular ophthalmic lenses (L) is proposed, in which a test piece of special, predetermined geometry is cut with the tool and then probed to obtain probe data. The method subsequently uses the probe data to mathematically and deterministically identify the necessary tool/machine calibration corrections in two directions (X, Y) and three directions (X, Y, Z), respectively, of the machine. Finally these corrections can be applied numerically to all controllable and/or adjustable axes (B, F1, X, Y) of the machine in order to achieve a (global) tool/machine calibration applicable to all work pieces within the machines operating range. As a result two-dimensional (2D) tool/machine calibration and three-dimensional (3D) tool/machine calibration, respectively, can be performed in a reliable and economic manner.