The equation is:

where LC is the load constant (23 kg),

• 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, and
• 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 explanation of terms.

To use the "automatic" 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.
H = Horizontal Distance (cm) HM Factor 25 or less  1.00   30  0.83   40   0.63   50   0.50   60  0.42	HM 25 or less 30 40 50 60
Vertical Multipler (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 0  0.78  30   0.87  50  0.93   70   0.99   100   0.93   150   0.78   175  0.70  >175  0.00	VM 0 30 50 70 100 150 175 >175
Distance Multipler (DM): The vertical distance (D, in cm) that the load travels.
D = Lifting Distance (cm) DM Factor 25 or less 1.00  40   0.93   55   0.90  100   0.87   145  0.85   175  0.85  >175  0.00	DM 25 or less 40 55 100 145 175 >175
Asymmetric Multipler (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	AM 90° 60° 45° 30° 0°
Frequency Multipler (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 Lifting While  Stooping One Hour or Less Over One Hour One Hour or Less Over One Hour 5 min  1.00  0.85 1.00  0.85   1 min   0.94   0.75   0.94   0.75   30 sec   0.91   0.65   0.91   0.65   15 sec   0.84   0.45   0.84  0.45   10 sec   0.75   0.27  0.75   0.27   6 sec   0.45   0.13  0.45   -  5 sec  0.37  -  0.37  -	FM = pick a value from (A) and (B). (A) Time Between Lifts Lifting While Standing One Hour or Less Over One Hour Lifting While Stooping One Hour or Less Over One Hour (B) FM 5 min. 1 min. 30 sec. 15 sec. 10 sec. 6 sec. 5 sec.
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).
C = Grasp CM Factor:  Standing  Stooping Good (handles) 1.00  1.00   Fair  1.00   0.95   Poor  0.90  0.90	CM = pick a value from (A) and (B). (A)Standing Stooping (B) CM Good (handles)FairPoor

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 =