Convert between inch-pounds (in-lbs), foot-pounds (ft-lbs), and Newton-meters (Nm)
To convert foot-pounds (ft-lbs) to Newton-meters (Nm), multiply your ft-lbs value by 1.356. For example, 100 ft-lbs equals 135.6 Nm.
Newton-meters (Nm) is the metric unit of torque, representing the rotational force equivalent to one newton of force applied perpendicularly at a distance of one meter from the axis of rotation.
Foot-pounds (ft-lbs) is the imperial unit of torque, measuring the rotational force equivalent to one pound of force applied perpendicularly at a distance of one foot from the axis of rotation.
The story of torque units like foot-pounds (ft-lbs), Newton-meters (Nm), and inch-pounds (in-lbs) is a fascinating journey that mirrors the evolution of engineering and scientific measurement. Before precise units, people relied on experience and feel, a method that worked for simple tasks but became inadequate as machines grew more complex. The need for standardized, repeatable measurements of rotational force, or torque, became paramount, driving the development of these essential units.
The foot-pound (ft-lb) and inch-pound (in-lb) emerged from the English engineering system, rooted in the familiar units of length (foot, inch) and force (pound-force). The foot-pound was first formally used in 1847. These units quantify torque as a force applied perpendicularly at a specific distance from an axis of rotation. The distinction between foot-pounds and inch-pounds simply scales the measurement to suit the application – inch-pounds being more common for smaller, more delicate fastening, while foot-pounds are used for larger, higher-torque applications like automotive engine specifications or tightening large bolts. While often colloquially referred to as "foot-pounds of torque," the technically precise terms are "pound-foot" or "pound-force foot" to avoid confusion with the unit of energy, the foot-pound.
The Newton-meter (Nm), on the other hand, is the internationally recognized standard unit of torque within the Système International d'Unités (SI). Named after Sir Isaac Newton, whose laws of motion laid the groundwork for understanding force and motion, and the meter, the fundamental SI unit of length, the Newton-meter represents the torque generated by one Newton of force applied at a perpendicular distance of one meter. This unit gained widespread adoption with the increasing global standardization of scientific and engineering measurements in the 20th century, making it the preferred unit for clarity and consistency across international borders and diverse industries. The shift towards the Newton-meter reflects a broader scientific effort to establish a coherent and universal system of measurement, a legacy of the Enlightenment and the pursuit of precise, reproducible science.