ASIL Risk Classification Tool
Enter Severity (S), Exposure (E), and Controllability (C) to classify risk into ASIL levels (QM, A, B, C, or D) using the ISO 26262 risk graph convention.
What this calculator is doing
This tool applies the common ISO 26262 risk graph approach: map Severity (S0-S3), Exposure (E0-E4), and Controllability (C0-C3) to an ASIL level.
Quick rules:
If any of S = 0, E = 0, or C = 0, the classification is QM (quality management). Otherwise, a lookup
table for S ∈ {1,2,3}, E ∈ {1,2,3,4}, C ∈ {1,2,3} is used.
We use the following well-established mapping (series combination of S, E, C). For compactness, each cell is the resulting ASIL.
For S1:
| E \ C | C1 | C2 | C3 |
|---|---|---|---|
| E1 | QM | QM | A |
| E2 | QM | A | A |
| E3 | A | A | B |
| E4 | A | B | B |
For S2:
| E \ C | C1 | C2 | C3 |
|---|---|---|---|
| E1 | QM | A | B |
| E2 | A | B | C |
| E3 | B | C | C |
| E4 | B | C | D |
For S3:
| E \ C | C1 | C2 | C3 |
|---|---|---|---|
| E1 | A | B | C |
| E2 | B | C | D |
| E3 | C | D | D |
| E4 | C | D | D |
Notes and assumptions:
• This is a simplified risk graph; actual item-level ASIL determination per ISO 26262 may consider operational
scenarios, independence, redundancy, and architecture.
• This tool does not provide legal or certification advice—use as an aid, not as a substitute for a full safety
case.
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