Abstract: A farrier's sighting instrument is designed as a portable, lightweight tool, easily carried by a farrier. It comprises a flat, transparent plate of a rectangular configuration, and sized to overlie the foot of a horse. The plate has a plurality of parallel indicia line sets on it, with the line sets arranged perpendicular to one edge of the plate. The lines in the line sets are spaced from one another by a uniform distance. A stop plate is attached to the one edge, and extends above the top surface of the flat transparent plate, with the stop plate located in a plane perpendicular to the plane of the parallel indicia lines.