Automotive PFMEA — assembly torque
Failure mode: under-torqued fastener at Station 4. S=8 (loose bracket, field return), O=4 (torque wrench drift), D=5 (visual audit only). RPN = 160 → critical. Action: add end-of-line torque audit.
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Free FMEA / RPN Calculator
Score Severity, Occurrence and Detection. Get an automatic Risk Priority Number and a Pareto-ranked review of failure modes. Export as CSV or PNG.
247 FMEAs calculatedDFMEAPFMEAHFMEASystem FMEA
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List failure modes
For each function or process step, list the ways it could fail and the effect on the user.
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Score S, O, D
Rate Severity, Occurrence and Detection on a 1–10 scale. The calculator multiplies them live.
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Prioritise action
Pareto-ranked review highlights the critical few. Export CSV or PNG for your quality record.
Set up your FMEA
Give the analysis a name and pick the FMEA type. Presets tune the rating-scale hints on the next screen.
Failure modes
Add one row per failure mode. Rate Severity (impact), Occurrence (how often), and Detection (how likely controls catch it) on 1–10. RPN = S × O × D updates live.
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Avg RPN
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Critical (>100)
Rating scale reference (1–10)
Severity — impact if the failure occurs. 10 = catastrophic / safety hazard without warning; 7–8 = customer dissatisfaction, rework; 4–6 = degraded function; 1–3 = minor nuisance or imperceptible.
Occurrence — expected frequency of the failure cause. 10 = almost certain (>1 in 2); 7–8 = frequent (1 in 20–1 in 100); 4–6 = occasional; 1–3 = remote to extremely unlikely.
Detection — likelihood that current controls will NOT catch the failure. 10 = no current control can detect; 7–8 = very poor detection; 4–6 = moderate; 1–3 = very likely to detect before reaching the customer.
Action thresholds — RPN >100 usually triggers corrective action; Severity ≥ 9 always triggers action regardless of RPN.
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Analysis review
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Top failure modes by RPN (Pareto view)
Recommended actions
Export & next steps
Export your FMEA and pick the next analysis step. Everything stays in your browser.
Related resources
Tip — Your FMEA stays saved in this browser's local storage. Close the tab and return later; you'll see a "Continue where you left off" banner on the start screen.
How to run an FMEA step by step
The calculator above walks you through the discipline. The steps below are the same workflow used in automotive PFMEA, medical-device DFMEA, and healthcare HFMEA — the format varies, the logic does not.
- Pick the FMEA type. Process FMEA analyses manufacturing or service-delivery process steps. Design FMEA analyses how a product could fail to perform its function. System FMEA covers software and subsystem interactions. Healthcare FMEA (HFMEA) handles clinical processes.
- List failure modes for each function or process step. For every function, write down the ways it could fail. "Under-torqued" is a failure mode; "loose bracket, field return" is the effect.
- Score Severity (1–10). How serious is the effect on the end user? 10 = catastrophic or safety hazard without warning; 7–8 = customer dissatisfaction, rework; 4–6 = degraded function; 1–3 = minor nuisance or imperceptible.
- Score Occurrence (1–10). How often is the failure cause expected to occur? 10 = almost certain (greater than 1 in 2); 7–8 = frequent; 4–6 = occasional; 1–3 = remote to extremely unlikely.
- Score Detection (1–10). How unlikely are current controls to catch the failure? 10 = no current control can detect; 7–8 = very poor detection; 4–6 = moderate; 1–3 = very likely to detect before it reaches the customer.
- Read the RPN. Risk Priority Number = Severity × Occurrence × Detection. Range 1–1,000. Below 40 is low risk; 40–100 moderate; above 100 typically triggers corrective action.
- Escalate Severity ≥ 9 regardless of RPN. Catastrophic effects cannot be tolerated even at low occurrence — act on them even if the RPN is low.
- Export and track. CSV download for the FMEA record; PNG summary for reports. Revisit the FMEA after any process or design change.
When to use FMEA vs other RCA tools
FMEA is a proactive risk assessment — used before something goes wrong. That makes it fundamentally different from the reactive methods (5 Whys, Fishbone) that analyse failures after the fact.
Good fits
- Pre-launch risk assessment for a new product (DFMEA) or process (PFMEA).
- Regulatory requirements — IATF 16949, AS9100, ISO 13485, 21 CFR Part 820 all require FMEA artefacts.
- D7 preventive action inside an 8D report — update the PFMEA after closure.
- Healthcare process redesign — HFMEA for medication, patient handoff, surgical procedures.
Not the right tool when
- You have one incident and need the root cause — use 5 Whys.
- You need to map candidate causes before narrowing — use Fishbone.
- You have count data and need priority — use Pareto.
- You need a customer-facing formal report — use an 8D; FMEA is internal.
Severity, Occurrence, Detection — rating scales
The AIAG-VDA FMEA handbook standardised the 1–10 scales below. Using the wrong scale is the second-most-common FMEA mistake (after treating RPN as a hard cutoff).
| Score | Severity (impact) | Occurrence (frequency) | Detection (controls) |
|---|---|---|---|
| 10 | Catastrophic / safety hazard without warning | Almost certain — >1 in 2 | Absolutely no chance of detection |
| 9 | Safety hazard with warning, regulatory non-compliance | Very high — 1 in 3 | Control unlikely to detect |
| 7–8 | Customer dissatisfaction, rework, recalls | Frequent — 1 in 20 to 1 in 100 | Very poor to poor detection |
| 4–6 | Degraded function, perceivable defect | Occasional — 1 in 500 to 1 in 10,000 | Moderate detection |
| 2–3 | Minor nuisance, cosmetic | Low — 1 in 150,000 | High chance of detection |
| 1 | Imperceptible | Extremely unlikely | Virtually certain detection |
FMEA examples across industries
Three short examples. Full worked case studies with complete RPN worksheets live in the FMEA examples article.
Healthcare HFMEA — medication
Failure mode: look-alike vial selected during prep. S=9 (patient harm), O=3 (rare), D=6 (barcode scan may miss). Severity ≥ 9 = act regardless. Tall Man lettering + barcode re-verification implemented.
Medical-device DFMEA — sterilisation
Failure mode: EtO residual above spec after sterilisation. S=9 (patient exposure), O=2 (process well controlled), D=4 (batch sample only). RPN = 72, but S=9 triggers 100% batch residual testing for next cycle.
Frequently asked questions
What is the Risk Priority Number (RPN)?
RPN = Severity × Occurrence × Detection. Each factor is scored 1–10, so RPN ranges 1–1,000. It is used to prioritise which failure modes get corrective action first. Higher RPN = higher priority.
What is a "good" or "acceptable" RPN?
There is no universal threshold. Common industry practice: RPN under 40 is low risk, 40–100 moderate, over 100 typically triggers action. Many teams also act on any item with Severity ≥ 9 regardless of RPN, because catastrophic effects cannot be tolerated even at low occurrence.
What is the difference between DFMEA and PFMEA?
DFMEA (Design FMEA) analyses failures in product design — how the part could fail to perform its function. PFMEA (Process FMEA) analyses failures in the manufacturing or service process that could produce a defective output. Both use the same S × O × D scoring but different rating scales. The FMEA complete guide covers both in detail.
What is HFMEA?
HFMEA (Healthcare FMEA) is a variant developed by the VA National Center for Patient Safety. It uses a 4×4 hazard matrix instead of the standard 10×10 RPN, and prioritises by Severity first. Use HFMEA for clinical processes: medication administration, patient handoffs, surgical procedures. See healthcare FMEA examples.
How does FMEA fit into a 5 Whys or 8D workflow?
5 Whys and 8D are reactive — used after something has gone wrong. FMEA is proactive and fits at two points: (1) before launch, to surface risks early; (2) as D7 preventive action inside an 8D, to update the PFMEA so the failure mode cannot recur.
Can I save my FMEA and come back later?
Yes. The tool auto-saves to your browser's localStorage after each change. When you return to the page you'll see a "Continue where you left off" banner. Your data never leaves your browser.
How do I export the FMEA?
Two options: CSV download (imports cleanly into Excel, Google Sheets, or any FMEA template), or PNG export of the summary view for reports and presentations. Both are one click from the Review screen.