NIOSH Lifting Equation

Overview

The NIOSH Lifting Equation is a biomechanically derived formula — revised in 1994 — for calculating the Recommended Weight Limit for specific lifting tasks and the Lifting Index that quantif ies the risk of musculoskeletal injury associated with those tasks. The equation accounts for six task variables — load weight, horizontal distance of the load from the body, vertical height of the lift, vertical travel distance, asymmetry of the lift, and frequency and duration of lifting — combining them into a Recommended Weight Limit below which most healthy workers can lift without significant risk of lower back injury. A Lifting Index greater than one indicates elevated risk — with higher values corre sponding to progressively greater risk of musculoskeletal injury.