How to fill in an FMEA
- Item or process step: what is being analysed, for example a process operation or a component function.
- Failure mode: how it can fail to meet the requirement, for example diameter oversize.
- Effect and severity (S): what the customer or the next process would experience, rated 1 (none) to 10 (safety, without warning).
- Cause and occurrence (O): why the failure happens and how often, from 1 (practically never) to 10 (almost certain).
- Current control and detection (D): how the failure or cause is caught before it reaches the customer, from 1 (certain detection) to 10 (no detection).
- Recommended action: what will lower the risk. Reduce occurrence first, improve detection second. Then rate again.
Rating guide
| Rating | Severity | Occurrence | Detection |
|---|---|---|---|
| 9–10 | Safety or legal, line stop | Very high, failure is almost certain | Cannot detect or no control |
| 7–8 | Loss of primary function | High, frequent failures | Low chance of detection |
| 4–6 | Reduced function or comfort | Moderate, occasional failures | Moderate, e.g. sampling inspection |
| 2–3 | Minor, noticed by some customers | Low, few failures | High, e.g. automated gauging |
| 1 | No effect | Remote, prevented by design | Certain, error-proofed |
Use the fishbone diagram to find causes and the capability study to support occurrence ratings with data.
Frequently asked questions
›How is the RPN calculated?
The risk priority number is severity × occurrence × detection, each rated from 1 to 10, so RPN ranges from 1 to 1000.
›What RPN is considered high?
There is no universal threshold. Many companies act on RPN above 100 to 200, and always on severity 9 or 10 regardless of RPN. The thresholds in this worksheet can be adjusted to your company rules.
›Why is severity 9 or 10 always prioritised?
Severity 9 and 10 mean a safety or regulatory effect. A low occurrence or good detection does not make such a failure acceptable, so it must be reviewed even when the RPN is low.
›Is this the AIAG-VDA action priority method?
No. This worksheet uses the classic RPN with a severity override, which is simple and widely used. The AIAG-VDA FMEA handbook replaces the RPN with an action priority table, which some customers require.
›Where is my FMEA saved?
In your browser storage on this device only. Nothing is uploaded. Export to CSV to keep a copy or share it, the file opens in Excel.