Repetitive Strain Risk Calculator

It's a simplified approximation of the Moore & Garg (1995) Strain Index, using the same six multiplied factors (intensity, duration, efforts per minute, posture, speed of work, and daily duration) drawn from the method's published multiplier tables, but simplified into discrete input bands rather than every graduated breakpoint in the original publication -- treat it as an educational screening tool, not a certified assessment. Speed of work is the published method's pace rating, separate from Repetitions per minute: Very Slow, Slow, and Fair pace all carry the baseline 1.0x multiplier, Fast pace applies 1.5x, and Very Fast pace applies 2.0x, on top of whatever Repetitions per minute already contributes.

The Strain Index itself is a product of exertion intensity, duration, frequency, posture, speed of work, and daily exposure duration -- Recovery time isn't one of those published factors, so this calculator keeps it separate, using it only to flag whether the worker gets adequate rest (Recovery adequate) and to raise Intervention priority when recovery is insufficient on top of an already-elevated Strain Index.

Repetitions per minute feeds into the Strain Index calculation through two separate factors -- duration of exertion per cycle and efforts per minute -- so a change in repetition rate compounds through both multipliers at once, typically moving the score more than an equivalent change in any single other input.

A Strain Index below 3 is classified Safe, 3 to 7 is Uncertain/Borderline and warrants closer job analysis, and above 7 is Hazardous and calls for intervention such as job redesign, tool changes, or task rotation -- these thresholds come from the published Strain Index literature correlating score ranges with reported incidence of distal upper-extremity disorders.

It uses discrete input bands rather than the published method's full continuous breakpoints, doesn't account for task variability across a shift, vibration or cold exposure, or individual worker susceptibility, and isn't a substitute for a full on-site Strain Index assessment by a qualified ergonomist for OSHA documentation or workers'- compensation purposes.