ISO 26262 vs IEC 61508

What is different

• Domain: IEC 61508 is generic and applies across industries that have no more specific derived standard; ISO 26262 applies specifically to road vehicles' electrical and electronic systems.
• Integrity classification: IEC 61508 uses Safety Integrity Levels (SIL 1–4) based on probability of dangerous failure; ISO 26262 uses Automotive Safety Integrity Levels (ASIL A–D, plus QM) derived from severity, exposure and controllability of the automotive hazard.
• Lifecycle detail: ISO 26262 provides substantially more automotive-specific detail, including part-specific requirements for hardware, software, production and supporting processes tailored to vehicle development and supply chains.
• Risk analysis method: IEC 61508 leaves the hazard and risk assessment method largely open; ISO 26262 specifies a defined method (severity, exposure, controllability) to derive ASIL ratings consistently across the automotive industry.

What overlaps

ISO 26262 is explicitly built on the same core concepts as IEC 61508: a safety lifecycle from concept through decommissioning, systematic and random hardware failure management, a safety case built from claims and evidence, and V-model-based development with verification and validation at each stage. Techniques for avoiding systematic failures — diverse redundancy, defensive programming, structured testing — are shared between the two, and competence and independence requirements for safety assessment follow a similar logic.

Both standards also share the principle that the integrity level drives the rigour of the process, not just the design: a high SIL or ASIL requires more independent verification, more structured analysis and more documented evidence, not simply a stronger design.

Which applies to you

• You develop electrical, electronic or programmable electronic safety-related systems for road vehicles: ISO 26262 is the applicable standard.
• You develop safety-related systems for a sector with its own derived standard (e.g. IEC 61511 for process industry, IEC 62061 for machinery, IEC 61513 for nuclear): use that derived standard, which itself traces back to IEC 61508.
• You develop safety-related systems for a sector with no derived standard: IEC 61508 applies directly.
• You supply a generic electronic component (e.g. a microcontroller or power module) into multiple sectors including automotive: qualify it against IEC 61508 generically and provide the specific evidence automotive customers need to build their own ISO 26262 case, since component-level qualification does not automatically confer an ASIL rating.

Frequently asked questions