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Motor specs list max continuous and burst current at recommended prop/voltage. Bench tests with watt meter at full throttle give actual loaded current.
ESC continuous rating ≥ motor max continuous current × 1.2 marginLarger props and higher cell count increase current at the same throttle. Current scales roughly with voltage and prop load torque.
I ∝ V × prop load torque (empirical — measure on thrust stand)ESC burst rating (10–30 s) handles punch-outs; continuous rating must cover sustained hover and cruise. Size for continuous, verify burst for acro.
ESC burst ≥ peak current × 1.1; ESC continuous ≥ avg high-throttle currentUpdated: July 2026
Motor max 35A continuous, 45A burst on 5×4.3 prop. ESC: 35A continuous minimum, 45A+ burst. Most builders use 40–50A ESC for headroom.
Cruise at 12A, peak 28A on 2806.5 motor. 30A continuous ESC sufficient; 40A provides margin for wind gusts without 60A overweight ESC.
Motor draws 38A max on 10×6 prop. 40A ESC meets spec; 50A adds cooling margin for summer flights with poor airflow in fuselage mount.
A 100C 1500 mAh battery can theoretically deliver 150A, but motor-prop combo determines actual draw. Size ESC to motor load, not battery capability.
An ESC rated 40A needs airflow in flight. Enclosed mounts without cooling effectively reduce rating — add heatsink or choose higher-rated ESC.
Undersized ESCs overheat and fail; oversized ESCs add unnecessary weight. This calculator determines required ESC continuous and burst current rating from motor max current, prop load, and battery voltage.