Myocardial edema significantly develops during current subnormothermic ex situ heart perfusion (ESHP) procedures, resulting in myocardial function decline during prolonged perfusion. A relatively high coronary blood flow (CBF) during ESHP is thought to be responsible for this high degree of myocardial edema formation. In this study, we present a novel tool to calculate CBF based on individual donor (sex and body weight) and perfusate (hemoglobin concentration, oxygen saturation, partial pressure of oxygen [PO2]) characteristics. The tool continuously evaluates the balance between myocardial oxygen consumption (MVO2) and delivery to facilitate adequate and preventing excess perfusion. Taking this personalized approach, the CBF can potentially be lowered while still providing sufficient oxygen to the donor heart. Furthermore, the tool automatically calculates MVO2, ΔPO2, and coronary vascular resistance during ESHP, which aids in the qualitative assessment of the heart before transplantation.