IEC 62366-1: Usability Engineering Process and FDA Guidance

IEC 62366-1 is the international standard for applying usability engineering to medical devices. Its full title is Medical devices, Part 1: Application of usability engineering to medical devices. It specifies a process a manufacturer follows to analyse, specify, develop and evaluate the usability of a device as it relates to safety. The process covers normal use, meaning correct use and use error. It can identify abnormal use but does not assess or mitigate it.

The standard sets out what to do and which records to keep. It does not tell a regulator what to put in a submission. For that, FDA has its own guidance, covered below. The human factors engineering page covers use errors, critical tasks and combination products. This page covers the standard and how it lines up with FDA's documents.

Editions and dates

The 2015 edition replaced IEC 62366:2007 and its 2014 amendment. Amendment 1 responded to 22 issues that experts had raised. Its introduction says it makes no fundamental change to the usability engineering process. It updates references to ISO 14971:2019 and ISO 13485:2016, and it aligns the order of risk control options with ISO 14971:2019. It also revises the definitions of user group and user profile, and removes the compliance check in the tailoring clause (4.3).

Part 2 is guidance, not requirements. ISO's catalogue lists its replacement, IEC TS 62366-2, as a committee draft approved for registration as a draft international standard on 3 August 2026. The catalogue says it is not intended for regulatory use.

FDA recognition

FDA lists IEC 62366-1 Edition 1.1 (2020-06, consolidated) and the US adoption ANSI/AAMI/IEC 62366-1:2015+AMD1:2020 in its Recognized Consensus Standards database under recognition number 5-129, with complete recognition. FDA says the database lists the standards for which it will accept a declaration of conformity. IEC 60601-1-6, the usability collateral standard for electrical equipment, is recognized separately (5-132). See IEC 60601-1.

Recognition makes the standard one way to support a submission. FDA's guidance still decides what the submission should contain.

The process, clause by clause

The standard's contents give the structure. Clause 4 holds general requirements and clause 5 holds the process. ISO sells the text, so this table paraphrases at the level of clause titles.

A user interface of unknown provenance (UOUP) is one developed earlier without adequate records of this process. Annex C gives a separate, shorter route.

Relation to ISO 14971

The standard is written to sit inside the risk management process. Clause 5.3 draws on the hazards and hazardous situations from the risk file. The consolidated edition includes a figure showing how the ISO 14971:2019 process and the usability engineering process relate. Clause 4.1.2 asks for risk control in the same priority as ISO 14971:2019, clause 7.1: inherently safe design, then protective measures, then information for safety and training.

Use-related hazards therefore belong in the same risk file as every other hazard. See ISO 14971 for the risk process, and IEC 62304 for software lifecycle requirements that run alongside.

How FDA's guidance differs

FDA's 2016 guidance is written for premarket review in the US, and it is a set of nonbinding recommendations. It cites the standard for several definitions and says its definitions are informed by, but not necessarily identical to, their sources. The differences that matter in practice:

• Terms. The standard calls the end-of-development test a summative evaluation. FDA calls it human factors validation testing and adds a footnote: "summative testing" can be defined differently, and some definitions omit essential components of validation testing as FDA describes it.
• What gets tested. The standard selects hazard-related use scenarios. FDA organizes validation around critical tasks, meaning user tasks that, if performed incorrectly or not at all, would or could cause serious harm to the patient or user. Harm includes compromised medical care. The guidance uses both terms. For a modified device that needs further testing, it says to focus on the hazard-related use scenarios and critical tasks the change affects.
• Severity over probability. FDA says the probability of a use error is very difficult to determine, so the severity of the potential harm is more meaningful for deciding whether to design the risk out or reduce it.
• Participants. FDA states that, in general, the minimum is 15 participants for each distinct user population, and that the minimum could be higher for specific device types. Populations are distinct when their characteristics would likely affect how they interact with the device or when their tasks differ. The guidance says employees should not serve as validation participants except in rare cases when all users are the manufacturer's employees. For users in the US, participants should reside in the US.
• Use error and design validation. FDA treats human factors validation as one portion of design validation. Under the QMSR the guidance's own footnote refers to ISO 13485:2016, and the text says design inputs must include usability requirements and applicable outputs of risk management.

Our reading is that FDA's use-related risk analysis does the work of clauses 5.2 to 5.5. FDA's guidance does not claim that equivalence.

FDA's May 2026 content guidance

The 2016 guidance covers how to run the work. A second guidance, finalized on 29 May 2026, covers what goes in the submission. FDA says it complements the first, and that the content guidance does not replace risk management. FDA noted a minimum of 60 days to operationalize it. Submissions received before 1 August 2026 are not expected to include the new information, and FDA will review it if provided.

The content guidance sorts each marketing submission into one of three human factors submission categories, using a decision flow built on the use-related risk analysis:

1. Category 1: a modified device with no change to the user interface, users, uses, use environment, training or labeling. The submission states that the changes do not affect human factors and describes any earlier evaluation it relies on.
2. Category 2: the submission gives a rationale for why there are no critical tasks, or no new or affected critical tasks, or why validation testing is not being submitted.
3. Category 3: a full human factors report that includes validation testing.

The guidance applies to 510(k), De Novo, PMA and HDE submissions. It defines the user interface the same way the standard does, including labeling and training. FDA said in a town hall that it intends to update the 2016 guidance with minor changes for consistency. The reissued 2016 guidance dated 3 August 2026 may reflect that. We did not compare the two versions line by line.

Not covered here

EU MDR requirements for usability, and notified body expectations, are outside this page.