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RPN calculator + Action Priority

Enter Severity, Occurrence, Detection — see both RPN (legacy AIAG FMEA 4th edition) and Action Priority (AIAG-VDA 2019). The AP lookup correctly handles the high-Severity cases that RPN used to dilute.

Your data never leaves the browser — all computation is client-side.

Severity (S)

1 = no effect on customer · 10 = breach of regulatory requirements / life-threatening

Occurrence (O) — Probability of occurrence

1 = failure practically impossible · 10 = failure practically certain (>1 in 2)

Detection (D) — Probability of detection

1 = failure almost certainly detected before shipping · 10 = current controls will not catch the failure

RPN vs Action Priority — in short

Why AIAG-VDA 2019 officially replaced RPN with AP, and what it means for your next PFMEA revision.

Formulas

RPN = S × O × D                  (1 to 1000)
AP  = lookup(S, O, D) → H/M/L    (AIAG-VDA 2019)

S = Severity     1–10
O = Occurrence   1–10
D = Detection    1–10

Why AP replaced RPN

Classic example: S=10, O=1, D=1 → RPN=10. Looks safe — RPN under 100. But Severity 10 means life-threatening or breach of regulatory requirements. AP correctly classifies this as Medium or High regardless of low O and D. AIAG-VDA 2019 made this safer for safety-critical components.

AP interpretation

High (H): Corrective actions are required before release. The team must demonstrate mitigation or justify why it is not possible.
Medium (M): Actions are recommended. Evaluate effectiveness or document why they are not needed.
Low (L): Actions are optional. Monitor at the next revision.

Should I still track RPN?

For new PFMEAs (from 2020+) AP is mandatory. For legacy PFMEAs from before 2020, you can keep tracking RPN as a KPI for historical comparability. Some OEMs (especially Japanese) still require RPN in parallel with AP — verify in customer CSR.

Frequently asked questions

Why two results — RPN and Action Priority?

RPN (Risk Priority Number) is a legacy metric from the AIAG FMEA 4th edition (S×O×D, 1–1000). Action Priority (AP) officially replaced it in AIAG-VDA 2019 — it uses a lookup table that treats high Severity separately (RPN could dilute it via low O and D). For new PFMEAs use AP. For legacy PFMEAs, or if your OEM still requires RPN (typical for Japanese customers), we show RPN as well — you see both.

What is the difference between AIAG FMEA 4th edition and AIAG-VDA 2019?

AIAG-VDA 2019 is a joint standard from AIAG (American) and VDA (German) published in 2019. It replaced both the AIAG FMEA 4th edition and VDA Volume 4. Key changes: 7-step process instead of 5, Action Priority instead of RPN, clearer Severity/Occurrence/Detection rating definitions, and the new "base FMEA" + "foundation FMEA" concepts linking DFMEA to PFMEA. For new projects from 2020+ AIAG-VDA 2019 is expected.

What RPN / AP do VW, Stellantis, BMW, Ford consider acceptable?

For AP: High requires mandatory actions, Medium recommended actions, Low optional. No OEM will allow a PPAP submission with an unresolved High AP on a safety characteristic. For RPN: traditional thresholds (RPN > 100 requires action, > 200 critical) are internal company policy, not an OEM standard. AIAG-VDA 2019 explicitly recommends switching to AP and not relying on a single RPN threshold. Always verify in customer CSR (VW Formel Q, Stellantis SQAM, Ford Q1).

How are Severity, Occurrence, Detection determined?

AIAG-VDA 2019 publishes rating tables for each dimension (10 levels). Severity: customer effect / regulatory compliance (1 = no effect, 10 = life-threatening). Occurrence: probability of occurrence under preventive controls (1 = practically impossible, 10 = >50% chance). Detection: probability of catching the failure before shipping (1 = almost certain detection, 10 = no detection). The team must reach consensus on the ratings for each failure mode.

Can I use this calculator instead of APIS IQ-RM or PLATO?

No — this is a calculator for the quick check of a single (S, O, D) triplet. APIS IQ-RM, PLATO SCIO, Siemens Teamcenter Quality, IQS PFMEA, etc. are full PFMEA editor tools with rows, characteristic linkages, revision history, hierarchy structure. Our PFMEA Brainstorm AI proposes failure modes + ratings for a single process step (requires login) — a full editor is on the roadmap.

Built by an AIAG-VDA PFMEA moderator

This calculator exists because I opened it for every PFMEA revision.

12 years in automotive quality. PFMEA expert at TRW Automotive Torino (Fiat platforms), QPC at HELLA Kočovce (launch PFMEAs for Nissan Navara and Mercedes-Benz programmes), today Production Quality Leader at HELLA-Forvia (24-person QA team, 2 factories). AIAG-VDA 2019 PFMEA / DFMEA moderator, VDA 6.3 Internal Auditor (Module A + B2).

I had to explain the RPN ↔ AP transition to the team dozens of times. This calculator is the output of that exercise — you see both metrics side by side and understand why AP correctly flags S=10, O=1, D=1 as Medium / High.

Read the full story →

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