Work out fmea risk priority number instantly with clear inputs, formula shown and shareable results.
RPN is severity x occurrence x detection, each rated 1 to 10. Its weakness is that very different risk profiles give the same product, so severity 9 or 10 items must trigger action regardless of RPN, and criticality (severity x occurrence) is reviewed alongside it. Newer FMEA standards replace RPN with an action priority table for this reason.
Risk priority number
RPN = severity x occurrence x detection
Criticality
Criticality = severity x occurrence
FMEA for safety-critical or regulated products must follow the applicable standard and be reviewed by qualified engineers. Severity 9 and 10 failure modes require action irrespective of any numerical score.
A 10-1-1 risk and a 1-10-10 risk both score 100, yet the first can injure someone and the second cannot. RPN thresholds alone therefore mis-prioritise safety-related failure modes.
Reduce occurrence by design or process change wherever possible. Improving detection only catches the failure after it happens and adds inspection cost without preventing anything.