A method for calibrating a tool of a cutting plotter, wherein the tool is in contact with a tool holder which is connected to a processing unit, the tool comprises a machining end extending between a first outer edge and a second outer edge along a lateral direction (X-direction), characterized in that the method comprises the steps of: h1. introducing, by means of a motorised displacement of the tool holder, a predetermined part of the machining end of the tool to a first initial position into a measuring zone of a measuring system of a tool-setting device, wherein the tool-setting device is connect to the processing unit; h2. determining, by means of the measuring system, a first width W1 of the tool in the measuring zone of the measuring system, wherein the first width W1 equals the distance measured along the lateral direction (X-direction) between the first outer edge and the second outer edge of the predetermined part of the machining end of the tool; h3. rotating, by means of a motorised rotation of a tool holder rotational axis, the predetermined part of the machining end of the tool over a predetermined first angle of rotation α12, wherein the first angle of rotation α12 is in the range of -90° to +90° with respect to the first initial position and different from 0°, and wherein the tool holder rotational axis is substantially perpendicular to the measuring zone of the measuring system; h5. determining, by means of the measuring system, a second width W2 of the tool in the measuring zone of the measuring system, wherein the second width W2 equals the distance measured along the lateral direction (X-direction) between the first outer edge and the second outer edge of the rotated predetermined part of the machining end of the tool; h6. determining, by means of the processing unit, an angular deviation δ of the tool with respect to an optimum machining direction according to a desired angular deviation accuracy on the basis of the determined first width W1 and the determined second width W2. h1. introducing, by means of a motorised displacement of the tool holder, a predetermined part of the machining end of the tool to a first initial position into a measuring zone of a measuring system of a tool-setting device, wherein the tool-setting device is connect to the processing unit; h2. determining, by means of the measuring system, a first width W1 of the tool in the measuring zone of the measuring system, wherein the first width W1 equals the distance measured along the lateral direction (X-direction) between the first outer edge and the second outer edge of the predetermined part of the machining end of the tool; h3. rotating, by means of a motorised rotation of a tool holder rotational axis, the predetermined part of the machining end of the tool over a predetermined first angle of rotation α12, wherein the first angle of rotation α12 is in the range of -90° to +90° with respect to the first initial position and different from 0°, and wherein the tool holder rotational axis is substantially perpendicular to the measuring zone of the measuring system; h5. determining, by means of the measuring system, a second width W2 of the tool in the measuring zone of the measuring system, wherein the second width W2 equals the distance measured along the lateral direction (X-direction) between the first outer edge and the second outer edge of the rotated predetermined part of the machining end of the tool; h6. determining, by means of the processing unit, an angular deviation δ of the tool with respect to an optimum machining direction according to a desired angular deviation accuracy on the basis of the determined first width W1 and the determined second width W2.