Abstract: The invention relates to a gauge or set of gauges for determining whether the bend angle, bend diameter, and end extension dimensions of a bent steel reinforcing bar used in structural concrete construction are within established allowable limits. The gauge comprises at least the outer marginal portion of a section of a circular disc, the disc having an outer perimeter which defines a diameter approximating the minimum bend diameter for a particular bar size and bar bend, the perimeter taking into account the deformations on said bar and indicating the starting and ending points of the bend, i.e., the points of tangency. Also included are methods of using such a gauge to determine whether a bar bend has less than the minimum bend angle and diameter and whether the end extension of such bend is less than the minimum allowable length.