Reliability and MTBF Calculator: Indicator Conversion and Prediction
What Are the Basic Indicators?
MTBF (mean time between failures) is the average working time between failures of a repairable product, and the failure rate lambda is the probability of failure per unit time; under the exponential distribution they are reciprocals, MTBF = 1/lambda. MTTR is the mean time to repair and availability A = MTBF/(MTBF + MTTR). The tool performs these conversions automatically and also converts quickly between FIT and MTBF so your indicators align with suppliers and industry handbooks.
How Is the Reliability Function Computed?
Under the exponential distribution, the reliability function is R(t) = e to the power of -lambda t = e to the power of -t/MTBF, the probability that a product still works at time t. Enter a target time to get the corresponding reliability, or enter a target reliability to derive the time reached. For non-constant failure rates such as wear-out, use the Weibull analysis tool instead; for series systems, failure rates add up to estimate the overall rate, and the tool includes system reliability stacking and configuration functions.
Application Scenarios
Typical uses are conversions in reliability reports (MTBF, failure rate and reliability back and forth), estimating spares and maintenance strategy, checking reliability indicators in tenders and contracts, and evaluating availability. It is also the base input for safety instrumented system SFF and PFDavg calculations, and for repairable systems it is often combined with maintenance strategy to evaluate downtime cost and optimize spares and staffing.
Outputs and Precautions
The tool outputs failure rate, MTBF, reliability at a specified time, unreliability and availability together with the formulas for verification. Note that the exponential assumption applies only to the random-failure period; mixing in early failures or wear-out data badly underestimates MTBF, so judge the failure mechanism first. Attach a statement of calculation conventions to outputs so audits and customer reviews are unambiguous.