Check whether a lift is within a safe weight limit in under a minute. The WISHA Lifting Calculator, from Washington State’s Department of Labor and Industries, is a quick screening version of the NIOSH Lifting Equation for lifting and lowering tasks.
How to use the WISHA Lifting Calculator
- Choose the units and enter the weight of the load (steps 1 and 2). Use the heaviest weight in the task.
- Choose where the hands are (step 3) at the riskiest point of the lift: above the shoulder, between the waist and shoulder, between the knee and waist, or below the knee.
- Choose how far out from the body the hands are (step 4), measured from the front of the body to the hands.
- Choose how often and for how long the lift is done (steps 5 and 6).
- Choose how much the body twists (step 7) during the lift.
- Read the lifting index and weight limit. The results table shows each step of the calculation.
- Print or save the result as a PDF to keep a record, or start over to check another lift.
For a full walkthrough with worked examples, read our step-by-step guide to the WISHA Lifting Calculator or the WISHA lesson in Mastering Ergonomics.
How the weight limit is calculated
- Unadjusted weight limit: the starting limit for where the hands are and how far out they reach, from 90 lb close to the body between the knee and waist down to 30 lb at an extended reach above the shoulder.
- Twisting adjustment: twisting 45° or more multiplies the limit by 0.85.
- Limit reduction multiplier: from 1.0 for infrequent lifts down to 0 for 10 or more lifts a minute for 2 hours or more.
- Weight limit is the unadjusted limit times the twisting adjustment and the limit reduction multiplier, and the lifting index is the weight of the load divided by it.
A lifting index of 1.0 or less means the load is within the weight limit, a nominal risk for most healthy workers. Above 1.0, the lift is hazardous and the task should be redesigned.
WISHA Lifting Calculator example
This is the distribution center example from our WISHA guide. A worker lifts 32 lb boxes from below the knee with the hands extended more than 12 in from the body, once a minute for more than 2 hours, twisting less than 45°.
- Unadjusted weight limit: 35 lb for below the knee at an extended reach. No twisting adjustment applies.
- Limit reduction multiplier: 0.75 for 1 lift a minute for 2 hours or more, giving a weight limit of 26.25 lb.
- Lifting index: 32 lb divided by 26.25 lb gives 1.22, so the lift is over the limit. Raising the boxes off the floor and bringing them closer to the body would raise the limit the most.
Load this example into the calculator.
When to use the WISHA Lifting Calculator
Use it to screen lifting and lowering tasks quickly and decide which ones need a closer look. For a detailed assessment with exact measurements, use the NIOSH Lifting Equation calculator. For pushing, pulling and carrying, use the Snook Tables calculator, and to score the posture during the lift, the REBA calculator.
Save and track lifting assessments
This calculator does not save your results. ErgoPlus ergonomics software keeps every WISHA assessment with its photos and notes, compares tasks across worksites and tracks improvements over time.
Source: Washington State Department of Labor and Industries lifting calculator, adapted from the Revised NIOSH Lifting Equation (Waters, Putz-Anderson, Garg and Fine, 1993).
FAQ
Common questions about the WISHA Lifting Calculator
What is the WISHA Lifting Calculator?
The WISHA Lifting Calculator is a screening tool for lifting and lowering tasks from the Washington State Department of Labor and Industries. It adapts the Revised NIOSH Lifting Equation into a few simple choices about where the hands are, how far out they reach, how often and how long the lifting goes on, and whether the body twists. The result is a weight limit for the task and a lifting index.
How is it different from the NIOSH Lifting Equation?
The WISHA calculator uses broad zones instead of exact measurements and leaves out the vertical travel distance and the hand grip, so it is quicker but less precise. Use it to screen tasks, and use the NIOSH Lifting Equation calculator when you need a detailed assessment of a lift.
What is a good lifting index?
A lifting index of 1.0 or less means the load is within the weight limit and poses a nominal risk for most healthy workers. Above 1.0, the load is over the limit and the task should be redesigned, for example by lightening the load, bringing it closer to the body, keeping it between the knees and shoulders, or lifting less often.
When does twisting count?
Choose 45° or more when the worker twists the torso 45° or more during the lift. Twisting that far multiplies the weight limit by 0.85.
Why is the weight limit zero?
At 10 or more lifts a minute for 2 hours or more, the limit reduction multiplier is 0, so no weight is acceptable. Reduce how often the lift is done, share it between workers, or use a mechanical aid.
Is this WISHA Lifting Calculator free?
Yes. There is nothing to sign up for, and you can print or save each result as a PDF. The calculator does not store your results. To save assessments, compare tasks and track improvements over time, use ErgoPlus ergonomics software.
