Abstract: The thickness of a printed product resting on a support is measured by a scanning unit which has two sensing elements which can be pressed back against the force of a spring. In a measuring zone, one sensing element is situated on the support and the other sensing element is situated on the printed product. By means of two laser sensors, the length of the distance between the one laser sensor and a measuring face of the first sensing element is measured and the length of the distance between the other laser sensor and a measuring face of the second sensing element is measured. From the difference between the lengths of these two distances, the thickness of the printed product can be determined. By a comparison of this thickness actual value with a prescribed thickness set value, it can then be established whether the product measured is complete or whether pages, parts, or supplements are missing or whether the product has too many pages, parts, or supplements.