Abstract: A gauge for measuring curvatures from tools such as lens lapping tools is disclosed. Such gauge includes a base providing a tool support and a gauge head movable relative to the base tool. The gauge head provides a pair of fixed posts having hemispherical ends and a movable post provided by a dial indicator located midway between the fixed posts. The posts are arranged so that they are movable into engagement with the curved surface of the tool when the measuring head is lowered. These three posts are located in a measuring plane and operate to determine the relative position of three points along the curved surface of the tool at the intersection of the tool surface and the measuring plane. The tool support is rotatable through 90 degrees to position the tool with the main curvature and cross curvature selectively positioned parallel to the measuring plane.