Safety & Workforce worked example

Fatigue Risk Score with severity of harm if a fatigued worker errs of 20 score: a worked example

What does the result look like when severity of harm if a fatigued worker errs reaches 20 score? The full calculation is worked below with real intermediate numbers. Use it when fatigue risk in safety and workforce needs a defensible ranking against other safety and workforce risks for the next review.

The inputs for this scenario

  • Severity of harm if a fatigued worker errs (1-10): 20 score (raised for this scenario; the documented default is 8)
  • How often fatigue conditions occur on this shift (1-10): 6 score (unchanged)
  • How hard fatigue is to detect before an error (1-10): 7 score (unchanged)

Working through the calculation

  • Applying the documented formula (Weighted score = severity × 0.40 + occurrence × 0.35 + detection × 0.25) to the inputs above produces each figure below.
  • At this operating point the engine returns 11.85 score for fatigue risk score, the number this scenario is built around.
  • At this operating point the engine returns 20 score for fatigue risk severity score.
  • At this operating point the engine returns 6 score for fatigue risk occurrence score.
  • At this operating point the engine returns 7 score for fatigue risk detection score.

How this compares with the baseline

  • Against the tool's baseline example, where severity of harm if a fatigued worker errs sits at 8 score and the headline result is 7.05 score, this scenario comes in 68.09% above the baseline at 11.85 score.
  • A figure at this level is achievable when severity of harm if a fatigued worker errs is genuinely sustained, not just peaked for a shift. It is a subjective risk ranking, not a physiological measurement; it does not replace hours-of-service data, sleep studies, or biomathematical fatigue models for regulated operations.

Results at a glance

  • Fatigue risk score: 11.85 score (headline result)
  • Fatigue risk severity score: 20 score
  • Fatigue risk occurrence score: 6 score
  • Fatigue risk detection score: 7 score

Run it with your numbers

  • Every input above is editable in the live Fatigue Risk Score calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.