Method for calibrating an apparatus for producing an object by means of additive manufacturing, wherein said apparatus comprises: - a process chamber for receiving a bath of material which can be solidified by exposure to electromagnetic radiation; - a support for positioning the object in relation to the surface level (L) of the bath of material ; and - a solidifying device for solidifying a selective layer-part of the material on the surface level (L) by means of electromagnetic radiation; wherein said method comprises the step of providing, on or near the support , a calibration marker (Mc) that faces the solidifying device , and the step of providing a calibration system with an imaging device that can be directed to said support , wherein the imaging device is arranged in such a way that an optical path of the imaging device , in use of the apparatus , coincides, preferably at least partly, with an optical path of the electromagnetic radiation of the solidifying device ; and wherein the method comprises the further steps of: a) determining, with the imaging device , a measure for the position of the calibration marker (Mc); b) controlling the solidifying device for making a solidifying marker (Ms) that relates to the calibration marker (Mc); c) determining, with the imaging device , a measure for the position of the solidifying marker (Ms); d) determining, with the calibration system , at least a correction vector (Vsc) based on the positions of both the calibration marker (Mc) and the solidifying marker (Ms) related to this calibration marker (Mc), wherein the step of determining a measure for the position of the calibration marker (Mc) comprises: - determining an expected position of the calibration marker (Mc); - controlling, based on said expected position, the apparatus and determining a resulting set position. - a process chamber for receiving a bath of material which can be solidified by exposure to electromagnetic radiation; - a support for positioning the object in relation to the surface level (L) of the bath of material ; and - a solidifying device for solidifying a selective layer-part of the material on the surface level (L) by means of electromagnetic radiation; a) determining, with the imaging device , a measure for the position of the calibration marker (Mc); b) controlling the solidifying device for making a solidifying marker (Ms) that relates to the calibration marker (Mc); c) determining, with the imaging device , a measure for the position of the solidifying marker (Ms); d) determining, with the calibration system , at least a correction vector (Vsc) based on the positions of both the calibration marker (Mc) and the solidifying marker (Ms) related to this calibration marker (Mc), wherein the step of determining a measure for the position of the calibration marker (Mc) comprises: - determining an expected position of the calibration marker (Mc); - controlling, based on said expected position, the apparatus and determining a resulting set position. - determining an expected position of the calibration marker (Mc); - controlling, based on said expected position, the apparatus and determining a resulting set position. <EOS>