Understanding Success Criterion 2.5.8: Target Size (Minimum)

Success Criterion 2.5.8 Target Size (Minimum) (Level AA): Targets have an area of at least 24 by 24 CSS pixels, except where:

Targets that allow for values to be selected spatially based on position within the target are considered one target for the purpose of the success criterion. Examples include sliders with granular values, color pickers displaying a gradient of colors, or editable areas where you position the cursor.

Are there issues with internationalization when describing inline links?

Are there issues with pop-over content overlapping targets triggering failures?

Status

This understanding document is part of the draft WCAG 2.2 content. It may change or be removed before the final WCAG 2.2 is published.

Intent

The intent of this Success Criterion is to ensure targets can easily be activated without accidentally activating an adjacent target. When targets are small, it is difficult for users with hand tremors and those who have difficulty with fine motor movement to activate them accurately. Providing sufficient size, or sufficient spacing between targets will reduce the likelihood of accidentally activating the wrong control.

This success criterion defines a minimum size, using larger sizes will help many people use targets more easily. Meeting 2.5.5 Target Size (Enhanced) is recommended whenever possible.

The requirement is for targets to be at least 24 CSS pixels in size, or for their size plus spacing be at least 24 CSS pixels. The targets offset is the size plus spacing between targets, measured from the farthest point of the target to the nearest point of each adjacent target. For example, a target of 20 by 20 CSS pixels would meet the requirement if it had a spacing of 4 px to any adjacent target. If the target is 24 by 24 CSS pixels or larger, no spacing between it and adjacent targets would be required.

There are three exceptions:

  1. If a target is smaller than 24 by 24 CSS pixels but has sufficient spacing, it passes. The spacing is sufficient if the offset between the farthest edge of the target to the nearest edge of any neighboring target is 24 CSS pixels or greater. What edge of the target is farthest depends on the position of the neighboring target to which the offset is established. For example, if the neighboring target is above it, the farthest edge would be the bottom of the target, and the offset would be measured from this bottom edge to the bottom edge of the neighboring target above.
  2. The Success Criterion does not apply to inline targets in blocks of text – for example, text links inside a sentence or paragraph. When multiple links are embedded in blocks of texts in smaller text sizes, maintaining a 24 CSS pixels offset between links in adjacent lines of text would require a large line height which can be undesirable in many design contexts. Also, inline links such as footnote numbers common in scientific texts may sometimes have a width of well below 24 CSS pixels. Placed in a sequence, these links often have a horizontal offset of less than 24 CSS pixels. Stacked lists of links, as in navigation structures, do not count as inline links.
  3. If the spacing of the targets is essential to the information being conveyed, the "Essential" exception applies. For example, in digital maps, the position of pins is analog to the position of places shown on the map. If there are many pins close together, the offset between pins and neighboring pins will often be below 24 CSS pixels. It is essential to show the pins at the correct map location, therefore the Essential exception applies.

The requirement is independent of the zoom factor of the page; when users zoom in the CSS pixel size of elements does not change. This means that authors cannot meet it by claiming that the target will have enough spacing or sufficient size if the user zooms into the page.

While the Success Criterion primarily helps touch users by ensuring that activation with the 'fat finger' will not accidentally trigger adjacent targets, it is also useful for mouse or pen users. It reduces the chances of erroneous activation due to a tremor or some other input imprecision.

As mobile devices generally have internal heuristics to identify which link is closest, spacing can work as effectively as a larger target size.

Four rows of icons with measurements, the first three passing,the last failing the requirement.
Figure 1 In the top line of icons, the dimension of each icon target is 44 by 44 CSS pixels with no space in between, amply passing this Success Criterion. In the next row, the dimension of each icon target is 24 by 24 CSS pixels with no space in between, passing this Success Criterion. In the next row, the the same icon targets are only 20 by 20 CSS pixels but they have 4px space inbetween, passing this Success Criterion. In the last row, the the same icon targets are only 20 by 20 CSS pixels and have no space inbetween, failing this Success Criterion.
A row of buttons which are more that 44px wide and 20 CSS pixels high. There are no targets above or below.
Figure 2 The widths of the button with adjacent neighbors is above 24 CSS pixels, while the height is only 22 CSS pixels. However, the target height combined with the vertical spacing above and below exceeds 24 CSS pixels, therefore, the targets pass this Success Criterion.
A row of buttons only 20 CSS pixels high, with other targets flush below, and only 2px spacing above.
Figure 3 Fail: Two rows of buttons, all with a height of only 20 CSS pixels. In the top row, buttons all have sufficient width (above 24 CSS pixels). For the top row, targets below are flush, with no gap. The gap to the links above is o nly 2px wide. Therefore, the buttons in the top row fail the Success Criterion.
A dropdown menu - a pass example with menu items 24 CSS pixels high, and a fail example with menu items only 20 CSS pixels high.
Figure 4 A dropdown menu is shown. The PASS example has menu items which are 24 CSS pixels high. In the FAIL example, the menu items are only 20 CSS pixels high.
Three examples of a target adjacent to, or nested within, another target (see legend below)
Figure 5 Three examples of a person's profile image, which is supposed to be a target leading to another page, and a magnifying glass icon, which is supposed to open a lightbox view of the profile image. In the first example, the magnifying icon is outside the picture. Its horizontal dimension is 24 CSS pixels. The vertical dimension is below 24 CSS pixels but since there are no adjacent targets above and below, the target meets the Success Criterion. In the second example, the icon overlaps with the top-left corner of the image. The image, itself a target, is immediately adjacent to the loupe icon. Measuring from the top of the loupe icon to the nearest point of the image target shows that that the offset is only 20 CSS pixels. The second example therefore fails the Success Criterion. In the third example, the loupe icon sits inside the linked image. Since it is surrounded by a larger target, the icon target fails - the offset to the surrounding and immediately adjacent image target is only 20 CSS pixels at top and bottom.

Users with different disabilities have different needs for control sizes. It can be beneficial to provide an option to increase the active target area without increasing the visible target size. Another option is to provide a mechanism to control the density of layout and thereby change target size or spacing, or both. This can be beneficial for a wide range of users. For example, users with visual field loss may prefer a more condensed layout with smaller sized controls while users with other forms of low vision may prefer large controls.

Benefits

Having targets with sufficient size - or failing that, sufficient target spacing - can help all users who may have difficulty in confidently targeting or operating small controls. Users who benefit include, but are not limited to:

Examples

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

  1. C42: Using min-height and min-width to ensure sufficient target spacing

Key Terms

target offset

the distance measured from the farthest point of a target to the nearest point of the second target. Offset includes the target and spacing around the target. The target offset from A to B may be different then the offset from B to A, if the size of these targets differ.