IEC 62304 software safety class
Class A / B / C follows from the severity of harm a software failure can cause, after considering hardware risk controls.
How to use the IEC 62304 class helper
Answer three questions about the worst credible harm from a software failure and whether an independent hardware control limits it. Record the resulting class and its rationale in your risk management file, then score the underlying hazards with the ISO 14971 risk matrix and, for standalone software, check the SaMD IMDRF category. More helpers live in the free MedTech tools hub.
Need help scaling your software lifecycle to the right class?
The safety class sets how much architecture, unit verification, and documentation IEC 62304 expects. Book a Consultation with our clinical / regulatory engineering team to justify your classification in the risk file and right-size the software development plan.
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- What are IEC 62304 software safety classes A, B and C?
- IEC 62304 classifies medical device software by the harm a software failure could contribute to. Class A: the software cannot contribute to a hazardous situation, or cannot do so with unacceptable risk after external risk controls, so no injury or damage to health is possible. Class B: non-serious injury is possible. Class C: death or serious injury is possible.
- Can hardware or other external risk controls lower the software safety class?
- Yes. Since Amendment 1 (2015), classification considers risk control measures external to the software system, such as a hardware interlock or independent monitor the software cannot defeat. Those controls, and why they are effective, must be documented in the ISO 14971 risk management file.
- What changes between Class A, B and C in the software lifecycle?
- All classes need a software development plan, software requirements, verification, release, maintenance, risk management, configuration management, and problem resolution. Class B and C add documented software architecture, integration testing, and unit verification. Class C adds detailed design of software units and additional unit acceptance criteria.
- Can different parts of the software have different safety classes?
- Yes, if you justify it. Software items inherit the class of the software system unless the architecture documents a rationale, typically segregation, showing that a lower-class item cannot contribute to the hazards of higher-class items.
- How does IEC 62304 relate to ISO 14971?
- IEC 62304 requires a risk management process that complies with ISO 14971. Software-related hazards and hazardous situations are identified in that process, and the resulting severity of possible harm drives the software safety class and the software risk controls you must verify.
- Does IEC 62304 apply to software as a medical device (SaMD)?
- Yes. IEC 62304 applies to medical device software, including software embedded in a device and software that is itself a medical device. For standalone health software products, the related IEC 82304-1 standard adds product-level requirements and references IEC 62304 for the software lifecycle.
Educational only. Not medical advice, not a regulatory determination, and not a substitute for qualified RA/QA, legal, clinical, or statistical counsel. IEC 62304 software safety class does not submit to FDA, Notified Bodies, or IRBs.
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Need help scaling your software lifecycle to the right class?
The safety class sets how much architecture, unit verification, and documentation IEC 62304 expects. Book a Consultation with our clinical / regulatory engineering team to justify your classification in the risk file and right-size the software development plan.
Book a Consultation