Safety & Workforce worked example

Fatigue Risk Score with severity of harm if a fatigued worker errs of 4 score: a worked example

This worked example runs the fatigue risk score numbers for a tougher week than the baseline: severity of harm if a fatigued worker errs of 4 score instead of the typical 8 score. Score fatigue risk from overtime, shift length, and rotation factors.

The inputs for this scenario

  • Severity of harm if a fatigued worker errs (1-10): 4 score (the input this scenario stresses; the baseline uses 8)
  • How often fatigue conditions occur on this shift (1-10): 6 score (held at the documented default)
  • How hard fatigue is to detect before an error (1-10): 7 score (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Weighted score = severity × 0.40 + occurrence × 0.35 + detection × 0.25.
  • Fatigue risk score works out to 5.45 score at these inputs, and this is the headline figure for the scenario.
  • Fatigue risk severity score works out to 4 score at these inputs.
  • Fatigue risk occurrence score works out to 6 score at these inputs.
  • Fatigue risk detection score works out to 7 score at these inputs.

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 22.7% below the baseline at 5.45 score.
  • Use it when reviewing shift schedules, overtime policy, or high-consequence night work and you need to rank which situations warrant fatigue countermeasures. A result at this level usually justifies acting on the stressed input before touching anything else, because every other figure in the table is downstream of it.

Results at a glance

  • Fatigue risk score: 5.45 score (headline result)
  • Fatigue risk severity score: 4 score
  • Fatigue risk occurrence score: 6 score
  • Fatigue risk detection score: 7 score

Run it with your numbers

  • To rerun this with your own numbers, open the live Fatigue Risk Score calculator, set severity of harm if a fatigued worker errs to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.