poundal/inch [pdl/in] Unit Converter

Definition of poundal/inch [pdl/in] unit

The poundal inch (pdl·in) is a unit of torque or moment of force in the foot–pound–second system. It represents one poundal of force acting at a perpendicular distance of one inch from a pivot: 1 pdl·in equals approximately 0.003512 newton-metres.

History of poundal/inch [pdl/in] unit

The poundal originated in the nineteenth-century British foot–pound–second (FPS) system, where it was defined as the force required to accelerate one pound mass at one foot per second squared. The name was introduced by James Thomson in 1876, helping distinguish absolute-force units from pound-force. Adding the inch as a lever-arm length produced the poundal inch, a derived torque unit. It appeared in older engineering, mechanics, and educational texts, but never achieved the international prominence of pound-force-based torque units. SI adoption later made newton-metres the preferred standard.

Applications of poundal/inch [pdl/in] unit

Today, the poundal inch is mainly encountered in historical references, legacy engineering documents, and unit-conversion software rather than contemporary design practice. It can express small torques in mechanics problems, especially when force is given in poundals and dimensions in inches. For modern reporting, values are usually converted to pound-force inches, pound-force feet, or newton-metres.

Complete list of poundal/inch [pdl/in] unit conversion