NIOSH recommended weight limit (U.S. units)
Used on the ASP, CSP and CHST. The worked example below is computed by code and checked against the source.
RWL = 51 × HM × VM × DM × AM × FM × CM
HM = 10/H, VM = 1 − 0.0075|V − 30|
DM = 0.82 + 1.8/D, AM = 1 − 0.0032A
LI = load ÷ RWL
H, V, D in inches; A in degrees; FM and CM from the manual's frequency and coupling tables. LI above 1 means elevated risk.
Worked example
H = 20 in, V = 15 in, D = 25 in, A = 30°, one lift every 5 min for 8 h (FM 0.85), fair coupling below 30 in (CM 0.95), 30 lb load.
51 × 0.50 × 0.8875 × 0.892 × 0.904 × 0.85 × 0.95 = 14.7 lb; LI = 30 ÷ 14.7 = 2.0
Run your own numbers: NIOSH lifting equation calculator.
Where it appears on the exam
ASP: ASP11 Domain 1, Mathematical Calculations
Blueprint: ASP11 Domain 1, task 9: manual lift parameters (NIOSH lifting equation)
Practice: NIOSH Lifting Equation
CSP: CSP11 Domain 6, Occupational Health and Applied Science
Blueprint: CSP11 Domain 6, task 4: ergonomics and human factors (lifting)
Practice: Exposure, Noise, Containment and Lifting Calculations
CHST: CHST5 Domain 1, Hazard and Risk Identification and Control
Blueprint: CHST5 Domain 1, knowledge 27: principles of ergonomics
Source
The formula comes from
NIOSH, Applications Manual for the Revised NIOSH Lifting Equation (DHHS Pub. No. 94-110)(opens stacks.cdc.gov in a new tab)“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)”
Questions
- What is the formula for nIOSH recommended weight limit (U.S. units)?
- RWL = 51 × HM × VM × DM × AM × FM × CM; HM = 10/H, VM = 1 − 0.0075|V − 30|; DM = 0.82 + 1.8/D, AM = 1 − 0.0032A; LI = load ÷ RWL. H, V, D in inches; A in degrees; FM and CM from the manual's frequency and coupling tables. LI above 1 means elevated risk.
- Will this formula be given on the BCSP exam?
- BCSP says the formula is included in the question whenever one is needed, unless the question is testing whether you know the formula. You can't bring a formula sheet into the exam, so learn what each formula does and when to use it.
BCSP on formulas at the exam
BCSP, What to Expect When Sitting for a BCSP Exam (item 7)(opens bcsp.org in a new tab)“For any question requiring a mathematical formula, the formula will be included within the exam question (unless the question is specifically testing your knowledge of a formula). You will not be provided or permitted to bring a formula sheet.”
Related
Checked 2026-10-16. Spot a problem? Email hello@passcited.com.