NIOSH Lifting Equation
Calculate the Recommended Weight Limit (RWL) and Lifting Index (LI) for a manual lifting task using the revised NIOSH equation and its multiplier tables. Fully offline.
Open NIOSH Lifting Equation →What is the NIOSH Lifting Equation calculator?
A calculator that works out the Recommended Weight Limit (RWL) and Lifting Index (LI) for a manual lifting task using the revised NIOSH (1994) equation and its multiplier tables. It's for ergonomic and manual-handling assessments and updates live as you type. Everything is computed in your browser and the inputs save on your device — for guidance only.
How to use NIOSH Lifting Equation
- Enter the load — Type the weight being lifted in kilograms.
- Measure the lift geometry — Fill in the horizontal location (H), vertical location at the origin (V), vertical travel distance (D) and asymmetry angle (A), all in centimetres or degrees.
- Set frequency and conditions — Add the lift frequency in lifts per minute, choose the work duration (≤1, ≤2 or ≤8 hours) and the coupling quality (Good, Fair or Poor).
- Read the results — The seven multipliers (HM, VM, DM, AM, FM, CM and the load constant LC) show live, along with the RWL in kg and the Lifting Index.
- Check the risk band — Read the colour-coded LI pill — Acceptable, Increased, High or Very high risk — to gauge the task.
Frequently asked questions
What is the Lifting Index telling me?
The LI is the load weight divided by the Recommended Weight Limit. An LI at or below 1.0 is generally acceptable; the higher it climbs above 1.0, the greater the strain risk for most workers.
Which version of the equation is used?
It uses the revised NIOSH (1994) equation: RWL = LC × HM × VM × DM × AM × FM × CM, with the standard 23 kg load constant and the published frequency-multiplier table.
Why is my Lifting Index showing as infinite?
If a measurement pushes a multiplier to zero — for example a horizontal reach or travel distance outside the valid range — the RWL becomes zero and the task is flagged as very high risk.
Are my measurements sent anywhere?
No. The whole calculation runs in your browser and your last inputs are saved locally on your device, so nothing is uploaded.
Can I rely on this for a formal assessment?
Treat it as guidance to support a manual-handling review, not a substitute for a qualified ergonomic or occupational-health assessment of the actual task.
Tips
- Measure the horizontal and vertical distances at the start of the lift (the origin) for the V and H inputs.
- Use lifts per minute for frequency — the calculator rounds up conservatively to the next tabulated value.
- Reducing the horizontal reach (H) usually raises the RWL most, so test it before changing the load.