NIOSH lifting equation calculator
Enter the lift geometry, frequency and coupling. You get every multiplier, the recommended weight limit (RWL) and the lifting index.
RWL = 51 × HM × VM × DM × AM × FM × CM (US units). FM and CM are looked up from the NIOSH tables; frequencies between table rows are linearly interpolated. A multiplier of 0 means the factor is outside the equation's limits (for example H over 25 in, V over 70 in, D over 70 in, A over 135°, or F over 15/min).
Formula and source
“The RWL is defined by the following equation: RWL = LC X HM X VM X DM X AM X FM X CM ... Load Constant LC 23kg 51lb; Horizontal Multiplier HM (25/H) (10/H); Vertical Multiplier VM 1-(.003|V-75|) 1-(.0075|V-30|); Distance Multiplier DM .82 + (4.5/D) .82 + (1.8/D); Asymmetric Multiplier AM 1-(.0032A) 1-(.0032A)”
FAQ
What is the revised NIOSH lifting equation?
RWL = LC × HM × VM × DM × AM × FM × CM. In US units the load constant is 51 lb, HM = 10/H, VM = 1 − 0.0075|V − 30|, DM = 0.82 + 1.8/D and AM = 1 − 0.0032A. FM and CM come from tables in NIOSH Publication 94-110.
What is the lifting index?
LI = load weight ÷ RWL. NIOSH's applications manual treats an LI above 1.0 as posing increased risk of lifting-related low back pain for some workers.
Is the NIOSH lifting equation an OSHA standard?
No. It's a NIOSH method, not an OSHA regulation. The ASP11 blueprint lists it twice: Domain 1 (“Calculate manual lift parameters (i.e., NIOSH lifting equation)”) and Domain 3 Ergonomics (as a quantitative analysis method).
For study and screening only. It isn't a substitute for a qualified ergonomic assessment.
The ASP11 blueprint lists the NIOSH lifting equation under Domain 1 (calculations) and Domain 3 (Ergonomics). Practice with worked NIOSH lifting equation questions.