What this calculator does
The calculator applies R(t) = exp[-(t/η)^β]. Characteristic life η is the point where reliability reaches 36.8%; shape β describes whether the failure intensity falls, stays roughly constant, or rises with age.
When to use it
Use it for wear-out, infant-mortality, and fatigue problems where an exponential constant failure rate would hide age effects.
Inputs and formula
Enter η and β from a documented Weibull fit and mission time in the same time unit. β must be positive; the method is only as representative as its underlying data set.
Worked example and interpretation
With η = 1,000 hours, β = 2, and a 500-hour mission, reliability is exp[-(0.5)^2], or about 77.9%. This means modeled survival—not guaranteed performance—for a comparable item.
Practical notes and limitations
Do not mix operating regimes, design revisions, or distinct failure modes into one fit without review. See the Weibull guide and parameter reference before basing a warranty or spares decision on it.