NIOSH Lifting Equation
Computes the revised NIOSH recommended weight limit and lifting index for a two-handed manual lift.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Load weight, lb
- 30 lb
- Horizontal distance from the ankles to the hands, inches
- 15 in
- Vertical height of the hands at the start of the lift, inches
- 30 in
- Vertical travel distance, inches
- 20 in
- Asymmetry angle of the trunk, degrees
- 0 deg
- Lifts per minute
- 1
- How long the lifting continues
- One hour or less
- Hand-to-object coupling
- Good: a handle, or a comfortable full-hand grip
Result: a recommended weight limit of 29.23 lb and a lifting index of 1.03
The tool opens with these values already filled in. Replace them with your own.
What the result means
- The equation
- A load constant of 51 lb multiplied by six task multipliers: horizontal distance, vertical height at the start, vertical travel, asymmetry angle, frequency with duration, and coupling.
- Lifting index
- The load divided by the recommended weight limit. At or below 1.0 is the range the equation is designed around.
- Above 1.0
- The task exceeds what the equation recommends for most healthy workers. It is a design number, not a prediction that this worker will be injured.
- A limit of zero
- A horizontal distance above 25 inches, a vertical height above 70, or an asymmetry angle above 135 degrees drives the limit to zero. That means the task is outside what the equation evaluates.
- What it covers
- Two-handed, smooth, unhurried lifts. Not carrying, pushing, pulling, one-handed lifts, lifting while seated or kneeling, or lifting in a constrained space.
- What it does not warn about
- Unstable loads, poor footing and hot or humid conditions are outside the equation, and it gives no signal of its own when they apply.
What you enter
- Load weight, lb
- Horizontal distance from the ankles to the hands, inches (above 25 puts the task outside the equation)
- Vertical height of the hands at the start of the lift, inches (above 70 puts the task outside the equation)
- Vertical travel distance, inches
- Asymmetry angle of the trunk, degrees (above 135 puts the task outside the equation)
- Lifts per minute
- How long the lifting continues
- Hand-to-object coupling
How this is calculated
Waters TR, Putz-Anderson V, Garg A, Fine LJ. Revised NIOSH equation for the design and evaluation of manual lifting tasks. Ergonomics. 1993;36(7):749-776. Applications Manual, DHHS (NIOSH) 94-110, 1994. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.