A method for estimating a shortening length of a sheet metal workpiece which is bent about n bending axes and by n bending angles alpha, - wherein a measuring arrangement with a first measuring element surface of a first measuring element and with a second measuring element surface of a second measuring element is used, - and wherein the measuring elements (20, 21) are formed by parts of the bending machine and the first and the second measuring element surfaces (22, 23) are arranged at an angle of 90° relative to one another, - and wherein the bent sheet metal workpiece comprises n+1 limbs extending along a straight extension line and n curved regions which are produced by bending the sheet metal workpiece and extend between two adjacent limbs, characterized by the following method steps: - determining the original length L0 of the sheet metal strip prior to bending of the sheet metal workpiece, - bending the sheet metal workpiece and placing the bent sheet metal workpiece against the measuring element surfaces (22, 23) with its outer surface, - determining the intersection/the intersections of straight extension lines of adjacent limbs or of straight lines parallel to the straight extension lines, said straight lines running at the surfaces of the limbs facing away from the respective bending axis, - determining the distances A1, A2 between the intersection/the intersections and the free ends (12, 13) of the limbs and determining the n -1 distances Bj between the intersections, - wherein the free ends (12, 13) of the limbs are measured using a contactless measuring method, - determining a tangent shortening T according to the formula: T = L 0 − ∑ i = 1 2 A i... n = 1 T = L 0 − ∑ i = 1 2 A i − B 1... n = 2 T = L 0 − ∑ i = 1 2 A i − ∑ j = 1 n − 1 B j... n ≥ 3 - wherein a measuring arrangement with a first measuring element surface of a first measuring element and with a second measuring element surface of a second measuring element is used, - and wherein the measuring elements (20, 21) are formed by parts of the bending machine and the first and the second measuring element surfaces (22, 23) are arranged at an angle of 90° relative to one another, - and wherein the bent sheet metal workpiece comprises n+1 limbs extending along a straight extension line and n curved regions which are produced by bending the sheet metal workpiece and extend between two adjacent limbs, characterized by the following method steps: - determining the original length L0 of the sheet metal strip prior to bending of the sheet metal workpiece, - bending the sheet metal workpiece and placing the bent sheet metal workpiece against the measuring element surfaces (22, 23) with its outer surface, - determining the intersection/the intersections of straight extension lines of adjacent limbs or of straight lines parallel to the straight extension lines, said straight lines running at the surfaces of the limbs facing away from the respective bending axis, - determining the distances A1, A2 between the intersection/the intersections and the free ends (12, 13) of the limbs and determining the n -1 distances Bj between the intersections, - wherein the free ends (12, 13) of the limbs are measured using a contactless measuring method, - determining a tangent shortening T according to the formula: T = L 0 − ∑ i = 1 2 A i... n = 1 T = L 0 − ∑ i = 1 2 A i − B 1... n = 2 T = L 0 − ∑ i = 1 2 A i − ∑ j = 1 n − 1 B j... n ≥ 3