Abstract. The present study develops a conceptual design methodology for battery-powered mini-UAVs. The methodology is adapted to address the peculiar characteristics of battery-powered mini-UAV and rewrites master and sizing equations which are related to the airframe weight and weight portions of battery and propulsion system. Subsequently, a conceptual design flowchart of battery-powered mini-UAV is provided. Ultimately, the methodology is verified by comparing to an existing UAV (RQ-11B), and applied to size a new Mini-UAV design. Satisfying results indicate that this methodology is suitable for conceptual design of battery-powered mini-UAV.