Work out manual handling limit (niosh) instantly with clear inputs, formula shown and shareable results.
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.
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
Preliminary estimate only. Manual handling assessment should be carried out by a competent ergonomist using the full equation including frequency and coupling multipliers.
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.
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.
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.