Foot-Poundal to Joule Converter

About this calculator

The foot-poundal (ft·pdl) is a unit of energy from the little-used foot-pound-second (FPS) absolute system, where force is measured in poundals rather than pounds-force — distinguishing it from the more familiar foot-pound (ft·lbf) used in engineering. One foot-poundal equals exactly 0.0421401 joules, derived from the definitions of the foot, pound mass, and poundal (the force that accelerates one pound mass at one foot per second squared).

The unit rarely appears outside of older British physics and engineering textbooks, historical technical literature, and a handful of legacy mechanical engineering problems that specify torque or energy in poundal-based units, since the poundal system was largely abandoned in favor of the gravitational (pound-force) system and, eventually, SI.

This calculator converts a foot-poundal value to joules using the exact conversion factor, saving students working through older textbook problems, translators of historical engineering documents, and physics hobbyists from tracking down the poundal's precise definition themselves.