The invention relates to a calibration method for a printer having a mechanism for advancing a medium in a direction of media advance comprising the following steps: (a) providing a printhead, the printhead having a swath height in the direction of media advance; (b) providing an estimate of either the swath height or the characteristic of the mechanism; (c) printing a base pattern on a medium using the printhead; (d) printing an overlay pattern on the medium using the printhead to form an interference pattern; (e) advance the medium of a predetermined distance using the mechanism at a time between the printing of the base pattern and the printing of the overlay pattern; (f) analyze an optical evaluation of the interference pattern; (g) evaluate as either: (i) the swath height if the characteristic of the mechanism is known or estimated; or (ii) the characteristic of the mechanism if the swath height is known or estimated.