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Manual Handling Limit (NIOSH) Calculator

Work out manual handling limit (niosh) instantly with clear inputs, formula shown and shareable results.

About Manual Handling Limit (NIOSH) Calculator

The NIOSH lifting equation starts from a 23 kg load constant for an ideal lift and multiplies it by penalties for each departure from ideal: horizontal reach, hand height, vertical travel, trunk twist, frequency and grip quality. The horizontal multiplier, 25 divided by the reach in centimetres, is usually the most punishing, which is why keeping loads close to the body matters most.

Formulas

Recommended weight limit

RWL = 23 x HM x VM x DM x AM x FM x CM

Multipliers

HM = 25/H; VM = 1 - 0.003|V - 75|; DM = 0.82 + 4.5/D; AM = 1 - 0.0032A

Worked example

With the default values below, Manual Handling Limit (NIOSH) Calculator returns Recommended weight limit of 11.12. Change any input above and every figure here is recalculated in your browser.

Inputs used

Horizontal distance from the ankles to the handsaccepts 25–63 cm
40 cm
Height of the hands at the start of the liftaccepts 0–175 cm
75 cm
Vertical travel of the loadaccepts 0–175 cm
50 cm
Asymmetry angle of the trunkaccepts 0–135 °
30 °

Results

Recommended weight limit
11.12 kg
Horizontal multiplier
0.6250
Vertical multiplier
1.0000
Asymmetry multiplier
0.9040

Step by step

  1. 1Values used
  2. 2Recommended weight limit
  3. 3Multipliers
  4. 4Recommended weight limit= 11.12 kg
  5. 5Horizontal multiplier= 0.6250
  6. 6Vertical multiplier= 1.0000
  7. 7Asymmetry multiplier= 0.9040

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax or compounding frequency into account.
  • Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Preliminary estimate only. Manual handling assessment should be carried out by a competent ergonomist using the full equation including frequency and coupling multipliers.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Preliminary estimate only. Manual handling assessment should be carried out by a competent ergonomist using the full equation including frequency and coupling multipliers.

Frequently Asked Questions

How is the Manual Handling Limit (NIOSH) figure worked out?

RWL = 23 x HM x VM x DM x AM x FM x CM. The NIOSH lifting equation starts from a 23 kg load constant for an ideal lift and multiplies it by penalties for each departure from ideal: horizontal reach, hand height, vertical travel, trunk twist, frequency and grip quality.

Why is the load constant 23 kg?

It is the weight that 99 percent of male and 75 percent of female workers could lift safely under otherwise ideal conditions, derived from biomechanical, physiological and psychophysical criteria.

What values do I need to enter?

This calculator takes 4 inputs: Horizontal distance from the ankles to the hands, Height of the hands at the start of the lift, Vertical travel of the load, Asymmetry angle of the trunk. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.

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