The end-diastolic pressure-volume relation (EDPVR) is an important descriptor of passive cardiac pump properties. However, clinical utility has been limited by the need for measurement of pressures and volumes over relatively large ranges. In this protocol, we describe an algorithm to estimate the entire EDPVR in humans from a single measured pressure-volume (P-V) point. This algorithm was developed from observations made from accurately measured EDPVRs of human hearts, which indicated that when normalized by appropriate left ventricular volume scaling (to arrive at volume-normalized EDPVRs, EDPVR(n)) EDPVR(n)s were nearly identical in all patients. In this protocol, we demonstrate how to use EDPVR(n)s to predict a second P-V point on the EDPVR, in which case the entire EDPVR can then be predicted. With recent advances for accurate noninvasive measurement of end-diastolic pressure and volumes, this protocol permits the assessment of passive properties in a broader range of research and clinical settings.