An inkjet printer is provided that is configured to store a plurality of pieces of gap information respectively corresponding to a plurality of examined sections discretely arranged along a head moving direction on a recording sheet, each of the plurality of examined sections including a corresponding one portion of top portions and bottom portions on the recording sheet, and calculate interpolation gap information to be interpolated over a whole width in the head moving direction of at least one of a plurality of segments, each of which has a width in the head moving direction defined by two adjacent sections of the plurality of examined sections, based on the stored gap information.