Abstract: A method of measuring planarity of strip in a strip-rolling line or a strip-processing line in which a measuring beam, a plurality of measuring beams or discrete measuring pins in an inclined pattern across a measuring roller, measures the tension forces acting upon the strip to form a force summation foundation across the strip width. A tension distribution function is derived from the force summation function by taking derivatives of the force-summation function with respect to the width dimension of the strip and, if desired, dividing that derivative by the thickness of the strip.