Reliability & maintenance engineering
Practical Reliability Engineering, Without the Guesswork.
Working calculators for the metrics you actually report — availability, MTBF, MTTR and OEE — each one showing the formula with your numbers substituted, the assumptions it rests on, how to read the result, and where the number stops being meaningful.
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Client-side, no signup, no data collected. Enter your figures and read the working.
Availability
Uptime/downtime and MTBF/MTTR methods, with inherent versus observed made explicit.
Open calculator →MTBF
Mean time between failures from operating time and failure count, in hours or days.
Open calculator →MTTR
Mean time to repair, with clear boundaries on what belongs inside repair time.
Open calculator →OEE
Availability × Performance × Quality, with the compounding effect shown step by step.
Open calculator →
Why this is different from a formula list
Most reliability content stops at the equation. Every metric here carries five things: formula, assumptions, interpretation, common mistakes, and the decisions it can support.
Formula, shown in full
Every result displays the equation with your own numbers substituted into it. Nothing is calculated behind a curtain.
Assumptions stated
Each tool lists the boundaries it relies on, including where a convention differs between organisations.
Interpretation, not verdicts
We explain what a result means without labelling arbitrary values as good or bad, and we do not invent benchmarks.
Common mistakes
The definition traps that quietly distort KPIs are called out where they occur, not buried in an appendix.
Decision use
Each metric is tied to the decisions it can actually support, and the ones it cannot.
No hidden agenda
No fabricated case studies, no invented industry averages, no copied text. Corrections are welcomed.
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