AviJoules transforms early-stage eVTOL mission analysis into a clear and practical experience by linking payload, endurance, and battery sizing into one interactive tool. Unlike generic calculators, it is tailored specifically for electric vertical takeoff and landing aircraft, offering engineers and enthusiasts a quick way to test design scenarios, evaluate trade-offs, and visualize performance impacts. With an elegant gradient interface and instant feedback, AviJoules turns complex aviation energy calculations into an accessible companion for innovation in electric flight.