How this calculation works
The Torque & Rotational Force Calculator computes rotational moment of force (τ) in Newton-meters (N·m), Foot-Pounds (ft-lbs), and Inch-Pounds (in-lbs) for mechanical engineering and automotive torque wrench specifications.
Mathematical formula and logic
Torque (τ) = Force (F) × Lever Arm Radius (r) × sin(θ). 1 N·m = 0.737562 ft-lbs.
Worked example
Applying 100 Newtons of perpendicular force (90°) at the end of a 0.5-meter wrench produces 100 × 0.5 × sin(90°) = 50.0 N·m (36.88 ft-lbs) of rotational torque.
Calculation assumptions
- Rigid pivot axis with zero mechanical flexure.
- Angle θ is measured between the lever arm vector and the applied force vector.
Frequently asked questions
What is torque?
Torque (also called moment of force) is the rotational equivalent of linear force. It measures the tendency of a force to rotate an object around an axis or pivot point.
How do I convert Foot-Pounds (ft-lbs) to Newton-Meters (N·m)?
Multiply Foot-Pounds by 1.355818 to get Newton-Meters (e.g. 100 ft-lbs = 135.58 N·m).
Why does a longer wrench make loosening stuck bolts easier?
Because torque is directly proportional to lever arm length (τ = F × r), doubling the wrench length doubles the applied torque for the exact same human muscular effort.
Why is maximum torque achieved at 90 degrees?
The trigonometric sine function peaks at sin(90°) = 1.0. Pushing or pulling at any angle other than perpendicular reduces effective rotational leverage.
What is the difference between horsepower and torque in car engines?
Torque is the rotational twisting force produced by the engine (low-end pulling power). Horsepower is the rate at which that torque work is delivered over time: Horsepower = (Torque in ft-lbs × RPM) / 5252.