RPN calculator (FMEA)

Enter the Severity, Occurrence and Detection of a failure mode (1 to 10 each) and get the RPN and its priority instantly.

Severity (S)5

How serious the effect of the failure would be if it occurred

Occurrence (O)5

How often the cause that produces that failure happens

Detection (D)5

How likely it is NOT to be detected before it reaches the customer or the next process (10 = hard to detect)

RPN = 5 × 5 × 5

125

Medium priority

Indicative thresholds of this site (high from 200, medium between 100 and 199, low below 100) — they are not a fixed standard: each industry or company defines its own cut-offs according to its risk tolerance.

How it works

You move three sliders from 1 to 10: severity (how serious the effect of the failure is), occurrence (how often the cause happens) and detection (how likely it is not to be detected before it reaches the customer or the next process; 10 = hard to detect).

RPN (risk priority number) = severity × occurrence × detection, from 1 to 1,000. The tool classifies it: 200 or more, high priority; from 100 to 199, medium; less than 100, low.

Those cut-offs (100 and 200) are a reference of this site, not of the AIAG-VDA standard or any other standard: each company defines its own "act now" threshold. A high RPN helps rank which failure modes to attack first.

If you prefer to work in Excel, there is an FMEA spreadsheet in Excel with these same calculations.

Sources

These are the ones from the article where the theory behind this tool is developed.

Where does the method come from, and is there a real case with these three scores? It is in the article FMEA: anticipating failures before they happen.