Manual Handling / NIOSH Lifting Equation Calculator

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).

Task Measurements

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.

Frequency & Duration

Lifting Frequency (lifts/min) Average over a 15-minute sample period.

Work Duration

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0 lbs

Recommended Weight Limit

0.00

Lifting Index (LI)

—

Risk Category

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

Based on the Revised NIOSH Lifting Equation (Waters et al., 1994) and the associated Applications Manual. This tool evaluates a single lifting task only — it does not calculate the Composite Lifting Index (CLI) for multi-task jobs, and does not apply to lifting with one hand, while seated or kneeling, on ladders/scaffolds, unstable loads, high-speed lifting (>30 in/s), or wheelbarrows/shoveling. Frequency Multiplier values above 8 lifts/min are less commonly needed and worth double-checking against the original NIOSH Applications Manual table for a formal assessment. For customized calculators tailored to your organization, please contact Impact Tech Solutions.

Manual Handling / NIOSH Lifting Equation Calculator

Formula Reference (Revised NIOSH Lifting Equation, 1994)

Lifting Index Risk Categories

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