# NIOSH Lifting Equation - Calculating Recommended Weight Limit (RWL)

## What is the Revised NIOSH lifting equation?

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.

NOTE: Please see this alternate page for a functioning calculator.

See Assessing Relevant Handling Factors for an explanation of terms.

Horizontal Multiplier (HM): Horizontal distance (H, in cm) from the midpoint between the ankles to the hands while holding the object.

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

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

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

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

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).

• Fact sheet last revised: 2023-04-26