TorqueCalculator
Calculate rotational torque from applied force and lever arm length, or from electric motor horsepower and RPM speed.
Torque Parameters
Torque Output
Torque Calculator - Free Force x Distance & Power / RPM Solver: Calculate rotational moment of force, lever arm distance, mechanical advantage, and angular torque. Fast, interactive, and completely free with instant results.
How to Use the Torque Calculator
Select Calculation Mode
Choose Mechanical Lever Arm (τ = F × r) or Rotating Motor (Power & RPM).
Input Force & Radius
Enter force (Newtons, lbf) and distance length from rotational axis (meters, feet, inches).
Or Enter Motor Horsepower
Specify motor wattage or horsepower alongside shaft rotational speed in RPM.
Read Cross-Unit Torque
Instantly view equivalent torque in Newton-meters (Nm), foot-pounds (ft-lb), and inch-pounds (in-lb).
Rotational Mechanics: Torque, Lever Arms, and Shaft Power
Torque (also referred to as moment of force) represents the rotational equivalent of linear force in physics and mechanical engineering. Just as linear force causes an object to accelerate along a straight path, torque induces rotational acceleration about an axis, pivot point, or fulcrum. Understanding torque is fundamental to structural bolted joint design, gearbox engineering, and electric motor sizing.
The foundational formula defining static torque is τ = F × r × sin(θ), where F is applied force, r is the perpendicular distance from the rotational center to the point of force application (the moment arm), and θ is the angle between the force vector and the lever arm. When force is applied perpendicularly (θ = 90°), sin(θ) equals 1, maximizing rotational efficiency.
In rotating machinery—such as internal combustion engines, steam turbines, and industrial electric motors—torque is inextricably tied to mechanical power and rotational velocity. The governing thermodynamic relationship is Power = Torque × Angular Velocity (P = τ × ω). Because power is the product of torque and speed, operating a motor at low RPM requires massive torque to achieve equivalent horsepower.
Unit conversions in torque require careful dimensional precision. The SI metric standard is the Newton-meter (N·m). In American automotive and heavy industrial sectors, foot-pounds (ft-lb) and inch-pounds (in-lb) predominate. 1 N·m is equivalent to approximately 0.73756 ft-lb or 8.8507 in-lb. Unlike work or energy (measured in Joules), torque is a vector quantity and must never be expressed in Joules.
Key Advantages & Analytical Value
Dual Engineering Modes
Calculate static lever arm moments or dynamic rotating motor shaft torques.
Multi-Unit Conversions
Simultaneously generates Nm, ft-lb, in-lb, and kgf-m without manual conversion.
Motor Horsepower Support
Directly converts kW and horsepower (hp) at given RPM into delivered torque.
Angular Velocity Tracking
Calculates shaft angular speed in radians per second (ω = 2πN / 60).
Private Calculations
Process proprietary machine specifications and aerospace designs locally in-browser.
Real-Time Reactivity
Live computation updates dynamically on every slider and input change.
Frequently Asked Questions
Torque measures the instantaneous rotational twisting force generated by an engine or motor. Horsepower measures how fast that torque is applied over time (Power = Torque × RPM / 5252 in imperial units).
Electric motors produce maximum peak torque instantly from 0 RPM, unlike internal combustion engines which must rev up into a specific power band to produce peak torque.
Although both Torque and Energy share the base dimensions (Newtons × meters), Energy is a scalar quantity (work done along distance), while Torque is a vector cross-product perpendicular to the plane of rotation.
Torque scales linearly with lever arm length. Doubling the wrench length doubles the delivered torque for the exact same applied physical muscle force.
1 foot-pound (ft-lb) equals approximately 1.35582 Newton-meters (Nm).