Reference desk
Maintenance KPI Formulas
Formula definitions are useful only when the numerator, denominator, event rule, and time boundary are agreed.
| Metric | Formula | Use with care |
|---|---|---|
| MTBF | Operating time ÷ failures | Repairable assets; stable event rule. |
| MTTR | Active repair time ÷ repairs | State whether delays are excluded. |
| Backlog | Ready work hours ÷ weekly capacity | Exclude work not ready to schedule. |
| OEE | Availability × performance × quality | Use defensible ideal cycle time. |
| ROI | (Benefit − recurring cost) ÷ investment | Simple annual screening metric. |
Scope before comparison
Do not compare KPI values across sites until inclusion rules match. For example, contractor labor, planned outages, repeat failures, and production time can all change the story.
Related tools
MTBF, backlog, OEE, and metric definitions guide.