What is WCAG (Web Content Accessibility Guidelines)?
Definition WCAG (Web Content Accessibility Guidelines) is the W3C standard for making web content accessible to people with disabilities. The current version, WCAG 2.2, was published in October 2023 and organizes testable success criteria under four principles (perceivable, operable, understandable, robust) at three levels: A, AA and AAA. Level AA is what most laws and policies require.
How to fix it: WCAG 2.2 Checklist for Mobile Websites
How is WCAG structured?
WCAG is built in layers. Four principles contain 13 guidelines, and each guideline has testable success criteria with a number such as 1.4.3 and a level:
- A: the basics, such as text alternatives for images and keyboard access;
- AA: includes A and adds criteria such as a 4.5:1 contrast ratio, text that can be resized to 200%, and 24×24 px minimum tap targets;
- AAA: the strictest level, such as 7:1 contrast and 44×44 px targets. The W3C does not recommend requiring AAA for whole sites.
Versions are backward compatible: a page that meets 2.2 AA also meets 2.1 AA and 2.0 AA, with one exception: 2.2 removed 4.1.1 Parsing as obsolete. WCAG 2.0 dates from 2008 and 2.1 from 2018; 2.1 added most mobile-related criteria.
Criteria that matter most on phones
- 1.3.4 Orientation: content works in portrait and landscape;
- 1.4.3 Contrast (Minimum): 4.5:1 for normal text, 3:1 for large text;
- 1.4.4 Resize Text: text can be enlarged to 200% without loss of content;
- 1.4.10 Reflow: no two-way scrolling at 320 CSS px wide;
- 1.4.12 Text Spacing: nothing breaks when line and letter spacing grow;
- 2.5.8 Target Size (Minimum), new in 2.2: targets at least 24×24 CSS px or well spaced.
WCAG and the law
WCAG is a technical standard, not a law, but laws point to it. In the EU, the harmonized standard EN 301 549 behind the European Accessibility Act uses WCAG 2.1 AA for web content. In the US, the Justice Department's 2024 rule for state and local governments under ADA Title II adopts WCAG 2.1 AA. Our guides to the European Accessibility Act and ADA website compliance cover the details.
How MobileCheck checks it
MobileCheck tests a set of WCAG AA criteria on real phone screens: text contrast below 4.5:1 (3:1 for large text), tap targets under 24×24 CSS px, disabled zoom, text that breaks at 150% size, and content wider than the screen, plus automated accessibility checks. Automated tools can't verify every criterion; screen reader and keyboard testing still need a person.