A non-transitory computer-readable recording medium on which is recorded a calibration program executed by an image forming apparatus that prints a first chart including patches in a plurality of colors, the calibration program causing the image forming apparatus to function as
- a tone-characteristics correcting circuit that corrects tone characteristics of the image forming apparatus,
- wherein the tone-characteristics correcting circuit corrects the tone characteristics of the image forming apparatus to tone characteristics of another image forming apparatus based on a difference in color value of patches between the first chart and a second chart in a both-side print chart image, the second chart being printed by the other image forming apparatus corresponding to the first chart, the both-side print chart image being generated such that the first chart and the second chart are simultaneously photographed by an photographing device.