A method for measuring a thickness of a coating of a constructional unit, in particular a heat-compatible coating on a component of a gas turbine, includes measuring coordinates of the constructional unit three-dimensionally with a measuring device, in particular an optical scanner, before and after the coating, a thermal distortion of the constructional unit being recorded during the coating and the thickness of the coating being determined from a comparison of the measured constructional unit coordinates before and after the coating. The thermal distortion of the constructional unit is taken into account in the thickness determination of the coating by a comparison with at least one reference point at an uncoated location.