Understanding SC 2.5.5: Target Size (Enhanced) (Level AAA)

In Brief

Goal: Controls can be operated more easily, especially on touch screens.
What to do: Make custom targets at least 44 by 44 pixels.
Why it's important: Some people cannot tap small objects.

Success Criterion (SC)

The size of the target for pointer inputs is at least 44 by 44 CSS pixels except when:

Equivalent: The target is available through an equivalent link or control on the same page that is at least 44 by 44 CSS pixels;
Inline: The target is in a sentence or block of text;
User Agent Control: The size of the target is determined by the user agent and is not modified by the author;
Essential: A particular presentation of the target is essential to the information being conveyed.

Intent

The intent of this success criterion is to help users who may have trouble activating a small target because of hand tremors, limited dexterity or other reasons. If the target is too small, it may be difficult to aim at the target. Mice and similar pointing devices can be hard to use for these users, and a larger target will help them greatly in having positive outcomes on the web page.

Touch is particularly problematic as it is an input mechanism with coarse precision. Users lack the same level of fine control as on inputs such as a mouse or stylus. A finger is larger than a mouse pointer, and generally obstructs the user's view of the precise location on the screen that is being touched/activated.

The issue can be further complicated for responsive/mobile sites which need to accommodate different types of fine and coarse inputs (e.g. a site that can be accessed both on a traditional desktop/laptop with a mouse, as well as on a tablet or mobile phone with a touch screen).

While this criterion defines a minimum target size, it is recommended that larger sizes are used to reduce the possibility of unintentional actions. This is particularly relevant if any of the following are true:

the control is used frequently;
the result of the interaction cannot be easily undone;
the control is positioned where it will be difficult to reach, or is near the edge of the screen;
the control is part of a sequential task.

The targets on a screen can have different purposes and uses, and this Success Criterion specifies how each is to be handled.

Equivalent targets: If there is more than one target on a screen that performs the same action, only one of the targets need to meet the target size of 44 by 44 CSS pixels.

Inline: Content displayed can often be reflowed based on the screen width available. This is known as responsive design and makes it easier to read since you do not need to scroll both horizontally and vertically. In reflowed content, the targets can appear anywhere on a line and can change position based on the width of the available screen. Since targets can appear anywhere on the line, the size cannot be larger than the available text and spacing between the sentences or paragraphs, otherwise the targets could overlap. It is for this reason targets which are contained within one or more sentences are excluded from the target size requirements.

Note

If the target is the full sentence and the sentence is not in a block of text, then the target needs to be at least 44 by 44 CSS pixels.

Note

A footnote or an icon within or at the end of a sentence is considered to be part of a sentence and therefore are excluded from the minimum target size.

User Agent Control: If the size of the target is not modified by the author through CSS or other size properties, then the target does not need to meet the target size of 44 by 44 CSS pixels.

Essential: If the target is required to be a particular target size and cannot be provided in another way, while changing it would essentially change the information or functionality of the content, then the target does not need to meet the target size of 44 by 44 CSS pixels.

Benefits

Users who use a mobile device where touch screen is the primary mode of interaction
Users with mobility impairments, such as hand tremors
Users who use a mobile device in environments where they are exposed to shaking such as public transportation
Users who find fine motor movements difficult
Users who access a device using one hand
Users with large fingers, or who are operating the device with only a part of their finger or knuckle
Users who have low vision may better see the target

Examples

Example 1: Buttons: Three buttons are on-screen and the touch target area of each button is 44 by 44 CSS pixels.
Example 2: Equivalent target: Multiple targets are provided on the page that perform the same function. One of the targets is 44 by 44 CSS pixels. The other targets do not have a minimum touch target of 44 by 44 CSS pixels.
Example 3: Anchor Link: The target is an in-page link and the target is less than 44 by 44 CSS pixels.
Example 4: Text Link in a paragraph: Links within a paragraph of text have varying touch target dimensions. Links within paragraphs of text do no need to meet the 44 by 44 CSS pixels requirements.
Example 5: Text Link in a sentence: A text link that is in a sentence is excluded and does not need to meet the 44 by 44 CSS pixel requirement. If the text link is the full sentence, then the text link target touch area does need to meet the 44 by 44 CSS pixels.
Example 6: Footnote: A footnote link at the end of a sentence does not need to meet the 44 by 44 CSS pixels requirements. The footnote at the end of the sentence is considered to be part of the sentence.
Example 7: Help icon: A help icon within or at the end of a sentence does not need to meet the 44 by 44 CSS pixels requirements. The icon at the end of the sentence is considered to be part of the sentence.

Related Resources

Resources are for information purposes only, no endorsement implied.

Techniques

Each numbered item in this section represents a technique or combination of techniques that the WCAG Working Group deems sufficient for meeting this Success Criterion. However, it is not necessary to use these particular techniques. For information on using other techniques, see Understanding Techniques for WCAG Success Criteria, particularly the "Other Techniques" section.

Sufficient Techniques

Select the situation below that matches your content. Each situation includes techniques or combinations of techniques that are known and documented to be sufficient for that situation.

Ensuring that targets are at least 44 by 44 CSS pixels.

Advisory Techniques

Although not required for conformance, the following additional techniques should be considered in order to make content more accessible. Not all techniques can be used or would be effective in all situations.

Ensuring inline links provide sufficiently large activation target.

Failures

The following are common mistakes that are considered failures of this Success Criterion by the WCAG Working Group.

Failure of Success Criterion 2.5.5 due to target being less than 44 by 44 CSS pixels.

Key Terms

assistive technology

hardware and/or software that acts as a user agent, or along with a mainstream user agent, to provide functionality to meet the requirements of users with disabilities that go beyond those offered by mainstream user agents

Note

Functionality provided by assistive technology includes alternative presentations (e.g., as synthesized speech or magnified content), alternative input methods (e.g., voice), additional navigation or orientation mechanisms, and content transformations (e.g., to make tables more accessible).

Note

Assistive technologies often communicate data and messages with mainstream user agents by using and monitoring APIs.

Note

The distinction between mainstream user agents and assistive technologies is not absolute. Many mainstream user agents provide some features to assist individuals with disabilities. The basic difference is that mainstream user agents target broad and diverse audiences that usually include people with and without disabilities. Assistive technologies target narrowly defined populations of users with specific disabilities. The assistance provided by an assistive technology is more specific and appropriate to the needs of its target users. The mainstream user agent may provide important functionality to assistive technologies like retrieving web content from program objects or parsing markup into identifiable bundles.

Example

Assistive technologies that are important in the context of this document include the following:

screen magnifiers, and other visual reading assistants, which are used by people with visual, perceptual and physical print disabilities to change text font, size, spacing, color, synchronization with speech, etc. in order to improve the visual readability of rendered text and images;
screen readers, which are used by people who are blind to read textual information through synthesized speech or braille;
text-to-speech software, which is used by some people with cognitive, language, and learning disabilities to convert text into synthetic speech;
speech recognition software, which may be used by people who have some physical disabilities;
alternative keyboards, which are used by people with certain physical disabilities to simulate the keyboard (including alternate keyboards that use head pointers, single switches, sip/puff and other special input devices.);
alternative pointing devices, which are used by people with certain physical disabilities to simulate mouse pointing and button activations.

blocks of text

more than one sentence of text

content

information and sensory experience to be communicated to the user by means of a user agent, including code or markup that defines the content's structure, presentation, and interactions

CSS pixel

visual angle of about 0.0213 degrees

A CSS pixel is the canonical unit of measure for all lengths and measurements in CSS. This unit is density-independent, and distinct from actual hardware pixels present in a display. User agents and operating systems should ensure that a CSS pixel is set as closely as possible to the CSS Values and Units Module Level 3 reference pixel [[css3-values]], which takes into account the physical dimensions of the display and the assumed viewing distance (factors that cannot be determined by content authors).

essential

if removed, would fundamentally change the information or functionality of the content, and information and functionality cannot be achieved in another way that would conform

pointer input

input from a device that can target a specific coordinate (or set of coordinates) on a screen, such as a mouse, pen, or touch contact

Note

See the Pointer Events definition for "pointer" [[pointerevents]].

presentation

rendering of the content in a form to be perceived by users

structure

The way the parts of a web page are organized in relation to each other; and
The way a collection of web pages is organized

target

region of the display that will accept a pointer action, such as the interactive area of a user interface component

Note

If two or more targets are overlapping, the overlapping area should not be included in the measurement of the target size, except when the overlapping targets perform the same action or open the same page.

user agent

any software that retrieves and presents web content for users

user interface component

a part of the content that is perceived by users as a single control for a distinct function

Note

Multiple user interface components may be implemented as a single programmatic element. "Components" here is not tied to programming techniques, but rather to what the user perceives as separate controls.

Note

User interface components include form elements and links as well as components generated by scripts.

Note

What is meant by "component" or "user interface component" here is also sometimes called "user interface element".

web page

a non-embedded resource obtained from a single URI using HTTP plus any other resources that are used in the rendering or intended to be rendered together with it by a user agent

Note

Although any "other resources" would be rendered together with the primary resource, they would not necessarily be rendered simultaneously with each other.

Note

For the purposes of conformance with these guidelines, a resource must be "non-embedded" within the scope of conformance to be considered a web page.