This study assessed the comparability of two types of penile strain gauges using both a circular and a newly developed oval calibration device. A group of 25 sexually functional participants placed both an electromechanical and an indium/gallium-in-rubber strain gauge on the penis and viewed an erotic film. The electromechanical gauge as calibrated on the circular device resulted in greater penile circumference changes than the indium/gallium-in-rubber gauge. Mean circumference changes were not different for the two strain gauges when the oval calibration device was used. The use of an oval calibration device improves ecological validity of calibration of penile strain gauges. Standard inclusion of this method in studies on male sexual response will increase comparability of research findings.