Calculate required hover thrust, motor sizing, throttle percentages, and payload margins for quadcopters, hexacopters, and octocopters.
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The Drone Thrust Calculator sizes brushless motors and propellers for multirotors (quadcopters, hexacopters, octocopters). By analyzing All-Up Weight (AUW) against target Thrust-to-Weight Ratio, it establishes required grams of thrust per motor at hover and maximum throttle.
T_{\text{hover/motor}} = \frac{\text{AUW}}{N_{\text{motors}}} \quad ; \quad T_{\text{max/motor}} = \frac{\text{AUW} \times \text{TWR}}{N_{\text{motors}}}Where AUW is total flight weight in grams, N_motors is motor count, and target TWR dictates hover throttle percentage (Hover Throttle % = 1 / TWR × 100).
Scenario: A 5-inch freestyle quadcopter weighing 650g with battery and GoPro, targeting a 4.0:1 TWR.
AUW = 650 grams across 4 motors.
Hover Thrust Needed: 650 / 4 = 162.5 grams per motor.
Total Max Thrust Needed: 650 × 4.0 = 2,600 grams.
Max Thrust per Motor: 2,600 / 4 = 650 grams per motor (achieved at 100% throttle).
AUW stands for All-Up Weight. It is the complete flight-ready weight of the drone including the frame, electronics, motors, propellers, battery pack, cameras, and any additional payload.
A 2:1 TWR means the drone uses exactly 50% throttle to balance gravity. This provides linear, predictable control stick response, optimal motor efficiency, and adequate reserve thrust to fight wind gusts.
High KV motors spin faster on lower voltage and swing smaller propellers (e.g. 2400KV on 5-inch props). Low KV motors produce high torque to swing large propellers efficiently on higher voltage (e.g. 400KV on 15-inch props).
Multiply installed motor maximum thrust by total motor count, divide by your target TWR, and subtract your current empty airframe weight.
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