How To Calculate Motor Torque From RPM

Torque Formula:

\[ T = \frac{P}{\omega} \] \[ \omega = \frac{2\pi \times RPM}{60} \]

Torque (T):

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1. What Is Motor Torque Calculation?

Motor torque calculation determines the rotational force produced by an electric motor based on its power output and rotational speed (RPM). This is essential for motor selection, mechanical design, and performance analysis.

2. How Does The Calculator Work?

The calculator uses the torque formula:

\[ T = \frac{P}{\omega} \] \[ \omega = \frac{2\pi \times RPM}{60} \]

Where:

\( T \) — Torque (Newton-meters)
\( P \) — Power (Watts)
\( \omega \) — Angular velocity (radians per second)
\( RPM \) — Rotational speed (revolutions per minute)
\( 2\pi \) — Radians per revolution
\( 60 \) — Seconds per minute

Explanation: The formula converts rotational speed from RPM to angular velocity in radians per second, then divides power by angular velocity to obtain torque.

3. Importance Of Torque Calculation

Details: Accurate torque calculation is crucial for motor sizing, mechanical system design, performance optimization, and ensuring proper operation under load conditions.

4. Using The Calculator

Tips: Enter power in watts and RPM in revolutions per minute. Both values must be positive numbers for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is the relationship between torque and RPM?
A: For a given power, torque decreases as RPM increases, and vice versa. This inverse relationship is fundamental to motor performance characteristics.

Q2: Can I use horsepower instead of watts?
A: Yes, but you must convert horsepower to watts first (1 HP = 745.7 W) for accurate calculation with this formula.

Q3: Why is angular velocity in radians per second?
A: The standard SI unit for angular velocity is radians per second, which provides consistency in torque calculations using the power-torque relationship.

Q4: How does torque affect motor selection?
A: Torque requirements determine the motor size and type needed to overcome starting inertia and maintain operation under load conditions.

Q5: What are typical torque values for different motors?
A: Torque values vary widely by motor type and size, from fractional Nm for small DC motors to thousands of Nm for large industrial motors.