Canadian Centre for Occupational Health and Safety
Home > OSH Answers > Ergonomics > NIOSH Lifting Equation (revised)
The equation is:
LC x HM x VM x DM x AM x FM x CM = RWL
where LC is the load constant (23 kg) and other factors in the equation are:
For each value, look up the corresponding factor and use this number in the equation. See Assessing Relevant Handling Factors for explanation of terms.
To use the calculator, click on the values for each factor in the left hand column (or you can input your numbers directly into the second equation). Press the "Calculate RWL" button when you have finished selecting all of the values.
Horizontal Multiplier (HM): Horizontal distance (H, in cm) from the midpoint between the ankles to the hands while holding the object.
Vertical Multipler (VM): The vertical distance (V, in cm) of the hands from the ground at the start of the lift.
Distance Multipler (DM): The vertical distance (D, in cm) that the load travels.
Asymmetric Multipler (AM): The twisting angle (A) of the body while lifting, measured in degrees.
Frequency Multipler (FM): The frequency (F) of lifts and the duration of lifting (in minutes or seconds) over a workshift.
FM = pick a value from (A) and (B).
(A) Time Between Lifts Lifting While Standing
Coupling Multipler (CM): The quality of grasp (or coupling, C) classified as good, fair or poor and depends on the body position (either standing or stooping).
CM = pick a value from (A) and (B).
More information is available in other OSH Answer documents. Please see the other documents in the NIOSH Lifting Equation series.
You may be interested in these related products and services from CCOHS:
For further assistance with a particular workplace topic or issue, contact our Inquiries & Client Services team. This service is free, reliable, and confidential.
Document confirmed current on October 1, 2012
Document last updated on September 17, 2007
Copyright ©1997-2015 Canadian Centre for Occupational Health & Safety