About

While amp-draw calculators rely on observation, this Physics-Based estimator is designed for the planning phase. It answers the question, "Can this build fly?" by analyzing the relationship between All-Up Weight (AUW) and Propeller Efficiency.

This tool differentiates between Hover (fighting gravity) and Fast Forward flight. It uses the specific efficiency curve of electric motors (g/W) to determine the power required to generate lift equal to the drone's mass. This is the professional method for sizing batteries for industrial or long-range drones.

Formulas

The power required to hover (P_hov) is derived from the weight and efficiency factor:

{

P_hov = Weight_gramsEfficiency_g/Wt_min = Battery_Wh × 60P_hov

Fast forward flight typically requires 1.5 to 2.0 times the hover power due to drag and the vector decomposition of thrust.

Reference Data

Propeller Size	Typical Efficiency (Hover)	Application
3 inch	3-5 g/W	Cinewhoop / Racing
5 inch	4-6 g/W	Freestyle
10 inch	8-10 g/W	Long Range / Cinema
15 inch+	12-15 g/W	Agriculture / Survey

Frequently Asked Questions

AUW is the total takeoff weight of the drone, including the airframe, motors, electronics, battery, and any payload like a GoPro. Accurate weighing is essential for this calculation.

Motor manufacturers (e.g., T-Motor, Emax) publish thrust tables. Look for the "Efficiency (g/W)" column at the thrust level matching your hover weight (Weight / Number of Motors).

Actually, this depends on aerodynamics. For multirotors, hovering is energy-intensive because the prop fights dead air. In fast forward flight, "translational lift" can improve efficiency, but air resistance (drag) eventually overtakes these gains at high speeds.