ISO 9241 Part 400: Principles and requirements for physical input devices


ISO 9241-400:2007 Ergonomics of human-system interaction -- Part 400: Principles and requirements for physical input devices.


International Standard.

Lifecycle Phase

Create the user experience.

Type of Guidance

Principles and general recommendations.

Application Area

General Guidance.


This part of ISO 9241 describes generic ergonomic principles for the design and use of input devices, such as keyboards, mice and joysticks. It does not provide specific design guidance for these devices, but instead provides a background in the important ergonomic requirements that designers need to consider. The whole of the “400 series” will be devoted to input devices and this part is really the introduction to the series (the other parts in the series are listed in the next section, “The future parts of ISO 9241”). There are three key sections: (a) “definitions”, (b) “design requirements” and (c) “properties of input devices relevant for usability”.

The bulk of the standard (around 40% of the page count) is devoted to various definitions, from “click” through to “ulnar deviation”.  (In case you were wondering, a “click” is the “depression and release of a button or actuation point on an input device”).

The design guidelines are “Appropriateness” (the input device should match the user, the user’s tasks and the user’s work environment); “Operability” (its intended use should be obvious, predictable and consistent); “Predictability” (it should match user expectations); “Consistency” (it should behave in the same manner when used in similar situations); “User compatibility” (the design should match the anthropometric and biomechanical capabilities of users); “Feedback” (the device should let the user know when it is responding to the user’s actions); “Controllability” (the device should be responsive); and “Biomechanical load” (which should be minimised).

The properties of input devices relevant for usability include functional properties (such as keyboard slope); electrical properties (such as the thickness of cabling for a mouse); mechanical properties (such as the weight of a hand-held device); and interdependency with software.


Manufacturers of input devices and people that need to evaluate the quality of input devices. It is unlikely that anyone would read this part in isolation: it makes sense only as an introduction to the other parts in the “400 series”.

See Also

ISO 9241-4:1998 Ergonomic requirements for office work with visual display terminals (VDTs) -- Part 4: Keyboard requirements.

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