Manual Handling / NIOSH Lifting Equation Calculator
Formula Reference (Revised NIOSH Lifting Equation, 1994)
RWL = LC × HM × VM × DM × AM × FM × CM (LC = 51 lbs)HM = 10 ÷ H | VM = 1 − 0.0075×|V − 30| | DM = 0.82 + (1.8 ÷ D) | AM = 1 − 0.0032×A
Lifting Index (LI) = Load Weight ÷ RWL
Lifting Index Risk Categories
| LI ≤ 1.0 | Low risk — acceptable for nearly all healthy workers |
| 1.0 < LI ≤ 3.0 | Moderate risk — some workers may be at increased risk; redesign recommended |
| LI > 3.0 | High risk — unacceptable for most workers without redesign |
Methodology, interpretation & sources
Purpose. NIOSH = National Institute for Occupational Safety and Health. Calculates the Recommended Weight Limit (RWL) and Lifting Index (LI) for a single lifting task using the Revised NIOSH Lifting Equation (1994).
How to use the result. Start with source data you can verify, enter values on a consistent unit and time basis, and record the assumptions used. The main inputs on this page include Load Weight (lbs), Horizontal Location, H (inches) Distance from the midpoint between the ankles to the hands. Valid 10–25 in., Vertical Location, V (inches) Height of the hands above the floor at the start of the lift. Valid 0–70 in., Vertical Travel Distance, D (inches) Vertical distance the load travels between origin and destination. Valid 10–70 in., Asymmetry Angle, A (degrees) Angle between the sagittal plane and the load's plane. 0° = directly in front. Valid 0–135°., Coupling Quality Quality of the hand-to-object grip.. Re-run the calculation when those assumptions change rather than carrying an old result forward.
Decision use. Use this tool to support an ergonomic screening assessment and to identify where redesign or a more detailed review may be warranted.
Limitations. Scores and recommended limits are not a diagnosis. Observe the real task, force, frequency, posture, duration and worker variability before selecting controls.
Primary references. Use the current edition/version that applies to your jurisdiction and organization:
Editorial note. Prepared and maintained by Impact Tech Solutions. Editorially updated 28 September 2026. No individual professional credential is claimed on this page; high-consequence, statutory, tax, engineering or health decisions should be independently verified against the current primary source and, where required, a qualified professional.