How to use this calculator
For one item, enter constant failure rate or MTBF/MTTF and mission time. For systems, enter component reliabilities.
Formula and method
Exponential R(t)=e^(−λt), MTTF=1/λ. Series R=∏Rᵢ; parallel R=1−∏(1−Rᵢ).
Worked example
MTTF 1000 time units and mission time 100 gives R=e^−0.1≈0.904837.
Assumptions and supported scope
Constant hazard for exponential mode; independent components for system modes. Does not estimate hazard from censored data, repair renewal, common-cause failure or redundancy switching failures.
Method references
Method and worked example checked against the calculator implementation. About our methods · Report a correction