IEC 62366-1 is the international standard that defines a usability engineering process for medical devices, ensuring the user interface is designed to minimize errors in use that could harm patients or operators. Published as IEC 62366-1:2015 with Amendment 1:2020, it links usability work directly to device risk management.
What is IEC 62366-1?
IEC 62366-1, titled “Medical devices, Part 1: Application of usability engineering to medical devices,” specifies how manufacturers analyze, design, verify, and validate the usability of a device as it relates to safety. Usability engineering (often called human factors engineering, HFE) is the discipline of designing a user interface so people can operate it correctly under real conditions.
The standard lives in the design and development phase but feeds the whole lifecycle. It does not chase general ease of use or user satisfaction. Its scope is narrower: preventing errors in use that lead to harm. A companion document, IEC 62366-2, offers guidance, but only Part 1 carries the requirements you certify against.
Why IEC 62366-1 matters in medical device development
Use error is one of the most common roots of device-related harm. An infusion pump misread, a connector attached to the wrong port, an alarm silenced by accident: these failures often trace back to interface design, not component faults.
Regulators treat usability as a safety requirement. The U.S. FDA recognizes IEC 62366-1 and expects human factors evidence for many submissions, supported by its 2016 guidance on applying HFE to medical devices. Under EU MDR 2017/745, the general safety and performance requirements in Annex I require that risks from ergonomic features and the use environment be reduced. Notified bodies routinely audit the usability engineering file.
Getting this wrong is expensive. A failed summative evaluation late in development can force a redesign, delay a launch, or produce findings during an audit. Building usability in early costs far less than retrofitting it after the design freeze.
How the IEC 62366-1 process works
The standard frames usability engineering as a structured process that runs alongside risk management under ISO 14971. The main activities are:
- Prepare the use specification. Define intended users, uses, use environments, and patient population.
- Identify user interface and use-related characteristics connected to safety, including known or foreseeable use errors.
- Identify hazards and hazardous situations that could result from those use errors, and add them to the ISO 14971 risk file.
- Describe hazard-related use scenarios and select the most important ones for testing.
- Establish the user interface specification and an evaluation plan.
- Run formative evaluations during design to find and fix problems early.
- Run a summative evaluation near design freeze to validate that the finished interface is safe to use.
Formative testing is iterative and diagnostic. Summative testing is the final, validation-grade study, usually with representative users performing critical tasks. All of it is recorded in the usability engineering file (UEF), the documented evidence an auditor reviews. The process aligns with design controls under FDA 21 CFR Part 820.30 and with risk management, ensuring that usability and risk outputs remain consistent.
Common challenges and best practices
Teams often start usability work too late, treating it as a checkbox before submission. By then, the architecture is fixed, and findings are hard to act on. Start with the use specification at the concept stage.
A frequent mistake is confusing formative and summative studies. Formative work shapes the design; summative work proves it. Running one late study to serve both purposes tends to satisfy neither.
Another gap is weak traceability. Hazard-related use scenarios should clearly link to the risk analysis and the tasks tested in the summative evaluation. Auditors look for that thread. Vague task selection, too few participants, or unrepresentative users undermine the validity of the summative study.
Good practice keeps the usability engineering file current, aligns it with the ISO 14971 risk management file, and documents why each scenario was or was not tested. Define your critical tasks early, then design the interface so those tasks are hard to perform incorrectly.
How SJML helps with IEC 62366-1
SJML builds usability engineering into device design rather than bolting it on at the end. Its engineering teams develop electromechanical devices across mechanical, electronics, embedded, and software disciplines, with usability engineering to IEC 62366 and risk management to ISO 14971 handled together from concept through design transfer. Use specifications, hazard-related use scenarios, and the usability engineering file are developed alongside the design itself, with phase-gate reviews and change control. In-house labs support related safety testing, including IEC 60601 electrical safety and EMC, so interface and engineering evidence stay connected.
Talk to SJML’s engineering team →
Frequently asked questions
IEC 62366-1 is a voluntary consensus standard, but compliance is effectively expected. The FDA recognizes it, and the EU MDR requires that use-related risks be controlled. Following IEC 62366-1 is the most direct way to show notified bodies and regulators that usability has been engineered and validated, so most manufacturers treat it as required in practice.
Formative evaluation happens during design to find and fix usability problems early; it is iterative and diagnostic. Summative evaluation is the final validation study performed near design freeze with representative users completing critical tasks. Summative results demonstrate that the finished user interface can be used safely. Both belong in the usability engineering file.
The two run together. ISO 14971 governs overall risk management; IEC 62366-1 supplies the use-related side. Hazard-related use scenarios identified through the usability process feed the ISO 14971 risk analysis, and risk controls that depend on the user interface are validated through usability evaluation. The standards are designed to be applied in parallel, with shared outputs.
The usability engineering file (UEF) is the record of all usability work: the use specification, user interface characteristics, hazard-related use scenarios, the user interface specification, the evaluation plan, and the results of formative and summative testing. It also captures the rationale for scenario selection. Auditors and notified bodies review it as evidence of compliance.
Related terms
Usability Engineering · ISO 14971 · Human Factors Engineering · Design Validation · Design Controls
