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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.

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.

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 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 target area of each button is 44 by 44 CSS pixels.

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.

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.
  • Ensuring inline links provide sufficiently large activation target.

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.

  • none documented

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

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]].

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.

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