Abstract: A universal calibration apparatus for use with an ultrasonic transducer is described. The calibration apparatus is fabricated from an elongate block of metal. The calibration apparatus includes a first portion having a first curved section, located at a first end of the apparatus, and a second curved section adjacent the first curved section. The first curved section having a thickness less than the thickness of the second curved section. The calibration apparatus also includes a second portion, located adjacent to the first portion, that includes a flat elongate section having a plurality of calibration holes extending therethrough and a plurality of scribe lines located on a first surface. The calibration apparatus further includes a third portion, located at a second end, that includes a plurality of step sections and a plurality of notches. The notches extend from a first edge to a second edge of the apparatus. Each step section has a different thickness from the other step sections.