Drone Motor Calculator — Thrust, Power & Current
Enter your motor KV rating, battery voltage, propeller size and the number of motors to get the estimated static thrust, electrical power, and current draw for your drone. Great for sizing a battery and checking thrust-to-weight ratios before you build.
KV
V
in
in
Number of motors
%
Combined thrust of all motors at full throttle on the ground
- 1
Motor RPM
2,300 × 14.8 = 34,040 - 2
Prop factor (3.295 × D)^1.5
(3.295 × 5)^1.5 = 66.89Empirical disc-area scaling factor for the static thrust model. - 3
Thrust per motor
4.392 × 10⁻⁸ × 34,040 × 66.89 × 4.5 = 0.5 - 4
Total static thrust
0.5 × 4 = 2
How does this calculator work?
RPM = KV × battery volts. Static thrust per motor ≈ 4.4 × 10⁻⁸ × RPM × (3.3 × diameter_in)^1.5 × pitch_in. Electrical power uses an empirical RPM³ × D⁴ constant. Multiply by motor count for totals. Good for pre-build sizing; verify against the motor datasheet.
Formula
How this is calculated
A brushless motor's KV rating defines how many RPM it spins per volt of applied voltage. Multiply KV by the battery voltage to get the no-load RPM. The static thrust is then estimated with the widely-used RC-hobbyist empirical formula: Thrust (g) = 4.392 × 10⁻⁸ × RPM × (3.296 × D_in)^1.5 × P_in, where D is the propeller diameter and P is the propeller pitch (both in inches). This formula is a good approximation for standard-shaped props under still-air, full-throttle hover conditions.
Electrical power is estimated using a second empirical constant (RPM³ × D_in⁴ × 5.33 × 10⁻¹⁵) divided by the motor's mechanical efficiency. Current draw follows from P = V × I. These empirical constants are derived from averaged bench-test data across many motor/prop combinations; actual values can vary ±20% depending on the specific motor, propeller brand, and airframe vibration. Always verify against your motor's datasheet thrust table.
A good racing quadcopter typically aims for a 2:1 thrust-to-weight ratio at hover (total thrust ≈ 2 × all-up weight), so the total thrust figure here should be at least double your intended all-up weight. The g/W efficiency metric helps compare setups: higher is better for long-range efficiency; lower (more power for less thrust) is common in race-tuned builds.
Frequently asked questions
KV is the motor's velocity constant — the number of RPM the motor spins per volt applied, measured unloaded. A 2300KV motor on a 14.8 V (4S) battery spins at roughly 34,000 RPM before the prop load slows it down.
The formula uses an empirical average constant that works well for typical racing props but can be off by ±20% for unusual prop shapes, high-pitch props, or motors at partial throttle. Use the datasheet thrust curve as the ground truth; this calculator gives a fast sanity-check without bench testing.
Most builds aim for 2:1 at hover — the drone can support twice its own weight at full throttle. Racing quads target 5:1 or higher for aggressive manoeuvres. Cinematography drones often settle for 3:1 to balance payload, efficiency, and flight time.
TG we-Calculate Editorial Team. (2026). Drone Motor Calculator — Thrust, Power & Current [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/drone-motor-calculator
TG we-Calculate Editorial Team. "Drone Motor Calculator — Thrust, Power & Current." TG we-Calculate. 2026. https://we-calculate.com/calculator/drone-motor-calculator.
TG we-Calculate Editorial Team, "Drone Motor Calculator — Thrust, Power & Current," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/drone-motor-calculator
@misc{wecalculate_drone_motor_calculator, title = {Drone Motor Calculator — Thrust, Power & Current}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/drone-motor-calculator}}, year = {2026}, note = {TG we-Calculate} }
Did this calculator help you?