The use of the resuscitative endovascular balloon occlusion of the aorta (REBOA) device is expanding in adult trauma. Reports of its use in pediatric patients have been published, but no guidelines currently exist nor has it been Food and Drug Administration approved in pediatrics. This project develops a model to determine appropriate balloon inflation volumes in pediatric patients to guide potential use. Artificial aortas were three-dimensional (3D) printed using synthetic polymers. Segments were created based on aortic diameters from 289 pediatric trauma patients' computer tomography (CT) scans. These aortic segments were inserted into a circulatory system model featuring two branches to simulate abdominal and upper body perfusion (cerebral, cardiac, and upper extremities). Sonographic flow meters and pressure transducers were placed along the circuit, and measurements were recorded as a REBOA device was inflated in the aortic segment. A negative sigmoidal relationship was observed between device inflation and aortic flow occlusion, with the initial 50% of inflation causing a 10% reduction in flow, followed by a steep decline. With increasing inflation, distal aortic flow and pressure were found to have an inverse relationship with the upper body branch metrics. In conclusion, pediatric patients present with a range of vessel diameters that occlude at various REBOA balloon inflation volumes. This study provides a basis to establish initial inflation volumes for safe REBOA deployment in appropriate pediatric trauma patients.