Drone Motor Size Calculator

Motor Size Equation:

\[ \text{Motor Size (A)} = \frac{\text{Thrust (N)} \times \text{Voltage (V)}}{\text{Efficiency} \times \text{KV (rpm/V)}} \]

Thrust:

Voltage:

Efficiency:

decimal (0-1)

KV Rating:

rpm/V

Motor Size (Current Draw):

Unit Converter ▲

Unit Converter ▼

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1. What is the Drone Motor Size Calculation?

The Drone Motor Size calculation estimates the current draw (in Amperes) required for a drone motor based on thrust requirements, battery voltage, motor efficiency, and KV rating. This helps in selecting appropriate motors and ESCs (Electronic Speed Controllers) for your drone build.

2. How Does the Calculator Work?

The calculator uses the motor size equation:

\[ \text{Motor Size (A)} = \frac{\text{Thrust (N)} \times \text{Voltage (V)}}{\text{Efficiency} \times \text{KV (rpm/V)}} \]

Where:

\( Thrust \) — Required thrust in Newtons (N)
\( Voltage \) — Battery voltage in Volts (V)
\( Efficiency \) — Motor efficiency (decimal between 0 and 1)
\( KV \) — Motor KV rating in rpm per Volt

Explanation: The equation calculates the current draw needed to produce the required thrust at the given voltage, accounting for motor efficiency and speed constant (KV).

3. Importance of Motor Size Calculation

Details: Proper motor sizing is crucial for drone performance, battery life, and safety. Undersized motors may overheat, while oversized motors add unnecessary weight.

4. Using the Calculator

Tips: Enter thrust in Newtons (1kg ≈ 9.81N), battery voltage, motor efficiency (typically 0.7-0.9), and KV rating (found in motor specs). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: How do I convert grams of thrust to Newtons?
A: Divide grams by 1000 to get kg, then multiply by 9.81 (1kg = 9.81N). Example: 500g = 0.5kg = 4.905N.

Q2: What's a typical motor efficiency value?
A: Most brushless motors have 70-90% efficiency (0.7-0.9). Default is set to 0.85 (85%).

Q3: How does KV rating affect motor size?
A: Higher KV motors spin faster per volt but typically produce less torque, requiring more current for the same thrust.

Q4: Should I add a safety margin to the calculated value?
A: Yes, it's recommended to select components rated for at least 20-30% more than the calculated current.

Q5: What if I know desired current but need to find thrust?
A: Rearrange the equation: Thrust = (Current × Efficiency × KV) / Voltage.