NIOSH Lifting Equation - Calculating Recommended Weight Limit (RWL)

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What is the Revised NIOSH lifting equation?

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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:

  • HM, the Horizontal Multiplier factor
  • VM, the Vertical Multiplier factor
  • DM, the Distance Multiplier factor
  • FM, the Frequency Multiplier factor
  • AM, the Asymmetric Multiplier factor
  • CM, the Coupling Multiplier factor
  • RWL, the Recommended Weight Limit

For each value, look up the corresponding factor and use this number in the equation. See Assessing Relevant Handling Factors for an explanation of terms.

To use the calculator, click on the values for each factor (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.

H = Horizontal Distance (cm)HM Factor
25 or less1.00 

Vertical Multiplier (VM): The vertical distance (V, in cm) of the hands from the ground at the start of the lift.

V = Starting Height (cm)VM Factor
 30  0.87
 50 0.93 
 70  0.99 
 100  0.93 
 150  0.78 
 175 0.70
 >175 0.00

Distance Multiplier (DM): The vertical distance (D, in cm) that the load travels.

D = Lifting Distance (cm)DM Factor
25 or less1.00
 40  0.93 
 55  0.90
 100  0.87 
 145 0.85 
 175 0.85
 >175 0.00

Asymmetric Multiplier (AM): The twisting angle (A) of the body while lifting, measured in degrees.

A = Angle (degrees)AM Factor
90° 0.71 
 60°  0.81
 45°  0.86 
 30° 0.90
 0° 1.00

Frequency Multiplier (FM): The frequency (F) of lifts and the duration of lifting (in minutes or seconds) over a workshift.

F = Time Between Lifts FM Factor
Lifting While Standing:OR Lifting While Stooping:
One Hour or LessOver One HourOne Hour or LessOver One Hour
5 min1.000.851.000.85
1 min 0.940.750.940.75
30 sec0.910.650.910.65
15 sec0.840.450.840.45
10 sec0.750.270.750.27
6 sec0.450.130.45-
5 sec0.37 -0.37 -


FM = pick a value from both (A) and (B).

(A) Time Between Lifts 
Lifting While Standing

Lifting While Stooping


Coupling Multiplier (CM): The quality of grasp (or coupling, C) classified as good, fair or poor and depends on the body position (either standing or stooping).

C = GraspCM Factor:
Good (handles)1.001.00

CM = pick a value from both (A) and (B).




The revised NIOSH Lifting Equation is: 23 Kg x HM x VM x DM x AM x FM x CM= RWL
23 Kg x x x x x x =


or, input values directly in the equation below:
23 Kg x x x x x x =

Where can I get more information about the lifting equation?

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More information is available in other OSH Answer documents. Please see the other documents in the NIOSH Lifting Equation series.

  • Fact sheet last revised: 2023-03-01