Maintenance & Reliability worked example

Weibull Life Estimate with characteristic life, eta of 45,000 hr: a worked example

This scenario runs the weibull life estimate calculation on the strong side: characteristic life, eta of 45,000 hr, with every other input held at its documented default. Use it when screening expected life at a target percentile before doing a full Weibull analysis.

The inputs for this scenario

  • Characteristic life, eta: 45,000 hr (raised for this scenario; the documented default is 18,000)
  • Shape adjustment factor: 0.92 x (unchanged)
  • Target percentile factor: 0.7 x (unchanged)
  • Duty factor: 1 x (unchanged)

Working through the calculation

  • Applying the documented formula (Base percentile life = characteristic life, eta × shape adjustment factor × target percentile factor) to the inputs above produces each figure below.
  • At this operating point the engine returns 28,980 hr for weibull life estimate, the number this scenario is built around.
  • At this operating point the engine returns 28,980 hr for base percentile life.
  • At this operating point the engine returns 1 x for duty factor.
  • At this operating point the engine returns 41,400 value for eta times shape adjustment.

How this compares with the baseline

  • Against the tool's baseline example, where characteristic life, eta sits at 18,000 hr and the headline result is 11,592 hr, this scenario comes in 150% above the baseline at 28,980 hr.
  • Use it after fitting a Weibull distribution to failure or suspension data, when you need a single replacement interval for a PM task or spares plan. Treat this as a target state: the delta against the baseline quantifies what the improvement is worth before you commit to chasing it.

Results at a glance

  • Weibull Life Estimate: 28,980 hr (headline result)
  • Base Percentile Life: 28,980 hr
  • Duty Factor: 1 x
  • Eta Times Shape Adjustment: 41,400 value

Run it with your numbers

  • Every input above is editable in the live Weibull Life Estimate calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.