ADA Compliant Website

Digital accessibility and web performance have traditionally lived in separate silos. Accessibility teams focus on WCAG compliance, while SEO and engineering teams track Core Web Vitals to improve rankings and engagement. Yet for users - especially those with disabilities - these concerns are inseparable.

Slow loading, unstable layouts, and delayed interactions are not just performance issues; they also compromise user experience. They are access barriers.

This article provides a detailed exploration of how WCAG success criteria align with Core Web Vitals metrics.

WCAG and Core Web Vitals: Different origins yet shared outcomes!

WCAG: Functional accessibility

WCAG success criteria ensure:

• Content is perceivable by assistive technologies.
• Interfaces are operable with keyboards and alternative inputs.
• Interactions are understandable and predictable.
• Code is robust across user agents.

WCAG focuses on functional access, not speed.

Core Web Vitals: Experiential performance

Core Web Vitals measure:

• Largest Contentful Paint (LCP) - how quickly the main content appears.
• Interaction to Next Paint (INP) - how responsive the page is to input.
• Cumulative Layout Shift (CLS) - how visually stable the page remains.

Core Web Vitals focus on perceived user experience, not disability-specific access.

Performance problems become accessibility failures – why?

Performance issues disproportionately affect:

• Screen reader users (DOM updates and accessibility tree lag)
• Keyboard-only users (delayed focus response)
• Users with cognitive disabilities (unpredictable UI behavior)
• Users with motor impairments (missed or repeated interactions)

This is why many WCAG failures emerge only under poor performance conditions, even when markup appears correct.

Connecting the Dots: WCAG Success Criteria vs. Core Web Vitals

WCAG 1.3.2 - Meaningful sequence

Impacted aspect of Core Web Vitals: CLS

WCAG intent: Content must follow a logical order regardless of visual styling.

Performance reality:

When layout shifts occur after initial render, the visual order diverges from the DOM order. It is confusing for

• Screen reader users
• Users rely on spatial memory.
• Magnification users

Examples:

• Late-loading images are pushing paragraphs downward.
• Ads are injected above the reading position.
• Consent banners shifting headings mid-read.

Why CLS matters for accessibility:

CLS doesn’t just move pixels - it reorders meaning in time, violating meaningful sequence.

WCAG 2.4.3 – Focus Order

Impacted aspect of Core Web Vitals: CLS + INP

WCAG intent:

Focus must move in an order that preserves meaning and operability.

Performance reality:

• Layout shifts can cause focused elements to move off-screen.
• Delayed rendering can cause focus loss.
• Re-rendering components may reset focus.

Common failure pattern:

When content loads after the page is interactive, keyboard focus jumps unexpectedly or moves out of sequence.

Takeaway:

Reducing CLS protects not just visual stability but focus stability.

WCAG 2.1.1 - Keyboard Accessibility

Impacted aspect of Core Web Vitals: INP

WCAG intent:

All functionalities must be operable via keyboard.

Performance reality:

Keyboard events are input events. If JavaScript is blocked or overloaded:

• Key presses are delayed.
• Focus transition lag
• Controls feel “broken” despite being technically accessible.

INP as an accessibility signal:

High INP often reveals:

• Excessive event listeners
• Long main-thread tasks
• Inefficient component re-renders

This affects:

Keyboard users, switch device users, and voice input users equally.

WCAG 2.2.1 - Timing Adjustable

Impacted aspect of Core Web Vitals: INP

WCAG intent:

Users must have enough time to complete tasks.

Performance reality:

Slow interaction response effectively shortens available time, especially for:

• Users with motor impairments
• Users having issues navigate quickly, or they navigate carefully on purpose.

Example:

A form session expires before a user can complete and submit it if they need more time.

Insight:

INP directly influences whether users can complete time-sensitive actions reliably.

WCAG 1.4.10 - Reflow

Impacted aspect of Core Web Vitals: LCP + CLS

WCAG intent:

Content must adapt to small screens without loss of information.

Performance reality:

• Large hero elements often define LCP.
• Poorly sized responsive elements shift after load.
• Font swaps cause text reflow.

Accessibility impact:

Reflow failures + layout shift create:

• Horizontal scrolling
• Disappearing controls
• Increased cognitive load

WCAG 4.1.2 – Name, Role, Value

Impacted aspect of Core Web Vitals: INP (indirect)

WCAG intent: UI components must expose correct semantics.

Performance reality:

Custom JavaScript widgets often:

• Recreate native controls poorly.
• Increase scripting overhead
• Delay accessibility tree updates

Result:

Slow input response + unreliable screen reader output.

Best practice:

Native HTML controls are both more accessible and faster.

WCAG 1.1.1 – Non-text Content

Impacted aspect of Core Web Vitals: LCP

WCAG intent: Images must have text alternatives.

Performance reality: Hero images are frequently the LCP element.

Accessibility + Performance intersection:

• Optimized images load faster for better LCP.
• Alt text ensures content is perceivable if images fail or load slowly.

Pointers where WCAG and Core Web Vitals do not align

There are some specifications available either in WCAG or Core Web Vitals:

Key truth:

Passing Core Web Vitals does not guarantee accessibility, and passing WCAG is not a sign of good web performance. They both need separate, detailed attention.

However, this mapping is useful for businesses!

• Google explicitly frames Core Web Vitals as “real user experience”.
• WCAG guidelines emphasizes predictability, operability, and robustness.
• Assistive tech performance depends on browser responsiveness.

The overlap is functional, not regulatory - and that’s why it matters in practice.

Practical guidance for teams

For accessibility teams

• Treat CLS issues as focus and reading-order bugs.
• Include performance regressions in accessibility testing.
• Test with throttled devices and AT enabled.

For performance & SEO teams

• View INP as an input accessibility metric.
• Fix layout shifts as UX predictability issues.
• Avoid JS-heavy custom components.

For product owners

• Align Core Web Vitals and accessibility KPIs.
• Fund fixes that deliver dual compliance value.
• Avoid siloed audits.

Read more: Google SERP Improvements after website migration

Accessibility and performance share the same user

WCAG and Core Web Vitals may speak different languages, but they describe the same user experience reality.

When pages load predictably, respond quickly, and remain stable:

• Screen readers work better.
• Keyboard navigation feels reliable.
• Cognitive load decreases.
• Trust increases.

If it helps every user to complete their tasks without any friction, it is good to map WCAG success criteria to Core Web Vitals.

Bringing accessibility and performance together takes more than theory - it takes the right partner. We help organizations align WCAG success criteria with Core Web Vitals through automated and manual accessibility audit, website accessibility compliance remediation, ongoing monitoring, VPAT report / ACR, and support. By connecting compliance goals with real-world user experience metrics, teams gain clearer insights, faster websites, and more inclusive digital journeys. Reach out hello@skynettechnologies.com to move from guidelines to measurable results.