Calculate torque from force and lever arm, solve for force or distance, and convert between torque and power using RPM. Supports N·m, lb-ft, and more.
Angle between force and lever arm (90° for perpendicular)
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Torque (τ) measures rotational force around an axis. Our calculator helps you compute torque from force and lever arm distance, find the force needed for a given torque, or convert between torque and power for motors and engines.
Torque is the rotational equivalent of linear force. It measures how much a force causes an object to rotate around an axis. The SI unit is the newton-meter (N·m), while Imperial systems use pound-foot (lb-ft). Torque depends on three factors: the magnitude of the force, the distance from the axis (lever arm), and the angle between them. Mathematically, torque is the moment of a force: τ = r × F × sin θ, where r is the lever arm and θ the angle between force and arm — the rotational analog of Newton’s F = ma.
Torque Formula
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Force causes linear acceleration (push/pull), while torque causes rotational acceleration (twist). Torque equals force multiplied by the perpendicular distance from the rotation axis. The same force creates more torque with a longer lever arm.
Divide newton-meters by 1.3558 to get pound-feet, or multiply lb-ft by 1.3558 to get N·m. For example, 100 N·m ≈ 73.76 lb-ft.
Horsepower = (Torque × RPM) / 5252 for Imperial units (lb-ft and HP). In SI units, Power (W) = Torque (N·m) × Angular Velocity (rad/s). HP and torque curves cross at 5252 RPM.
Maximum torque occurs when force is perpendicular (90°) to the lever arm. At 0° or 180°, the force is parallel and produces no torque. The sine function (sin θ) in the formula accounts for this relationship.