SVG Accessibility Skill

Canonical source: examples/SVG_ACCESSIBILITY_BEST_PRACTICES.md in mgifford/ACCESSIBILITY.md This skill is derived from that file. When in doubt, the example is authoritative.

Apply these rules when creating, optimising, or reviewing SVG graphics. Only load this skill if the project contains SVGs.

Core Mandate

Outcome-based, not checklist-driven. Measure against real usage context: is the SVG perceivable, operable, and compatible with assistive technologies?

Pattern recommendations in this skill are grounded in cross-browser/screen reader testing by Carie Fisher (published on Smashing Magazine, updated at <https://cariefisher.com/a11y-svg-updated/>). When a pattern is labelled "Best in Show", "Use Caution", or "Not Recommended" below, those labels reflect her testing results across OS/browser/screen reader combinations.

Severity Scale (this skill)

Decorative SVGs — Hide Completely from AT

A decorative SVG that is not hidden from AT is a Moderate issue — it adds noise to the accessibility tree and forces screen reader users to listen to meaningless announcements.

Both attributes are required:

<svg aria-hidden="true" focusable="false">
  <!-- decorative icon — no title, no desc, no role needed -->
</svg>

• aria-hidden="true" removes the SVG from the accessibility tree entirely
• focusable="false" is required for IE/Edge legacy compatibility where SVGs

become focusable by default and appear in the tab order

Never use `role="presentation"` as a substitute for `aria-hidden="true"` on decorative SVGs. role="presentation" does not reliably suppress AT announcement across all browser/screen reader combinations.

When is an SVG decorative? If the same meaning is conveyed by adjacent visible text, or if the image is purely ornamental (borders, backgrounds, flourishes), it is decorative. If removing it would leave a user without information or context they need, it is meaningful.

Meaningful SVGs — Choosing the Right Pattern

Based on Carie Fisher's testing across NVDA, JAWS, VoiceOver (macOS and iOS), TalkBack, and Narrator:

SVG as <img> (external file reference)

Use <img> for simple, uncomplicated images. The SVG file loads separately — this is lighter and easier to maintain for icons used in multiple places, but offers less control over internals.

Best in Show — `<img>` patterns:

<!-- Pattern 2: <img> + role="img" + alt — RECOMMENDED -->
<img role="img" class="icon" alt="Download" src="download.svg">

<!-- Pattern 3: <img> + role="img" + aria-label — RECOMMENDED -->
<img role="img" class="icon" aria-label="Download" src="download.svg">

Use Caution:

<!-- Pattern 4: <img> + role="img" + aria-labelledby
     Works in most combinations but has gaps in some screen readers -->
<p id="cap1" class="visually-hidden">Download report</p>
<img role="img" aria-labelledby="cap1" src="download.svg">

Not Recommended:

<!-- Pattern 1: <img> + alt alone — inconsistent results, omit role="img" -->
<img alt="Download" src="download.svg">

Inline SVG — simple label only

Use inline <svg> when you need control over colours, animation, or internals.

Best in Show — inline SVG patterns (simple label):

<!-- Pattern 5: <svg> + role="img" + <title> — RECOMMENDED -->
<svg role="img" viewBox="0 0 24 24" xmlns="http://www.w3.org/2000/svg">
  <title>Download</title>
  <!-- paths -->
</svg>

<!-- Pattern 8: <svg> + role="img" + <title> + aria-labelledby — RECOMMENDED -->
<svg role="img" aria-labelledby="dl-title" viewBox="0 0 24 24">
  <title id="dl-title">Download</title>
  <!-- paths -->
</svg>

Use Caution:

<!-- Pattern 7: aria-describedby pointing to <title> — less reliable than
     aria-labelledby; some screen readers do not expose the description -->
<svg role="img" aria-describedby="dl-title7" viewBox="0 0 24 24">
  <title id="dl-title7">Download</title>
</svg>

Not Recommended:

<!-- Pattern 6: <svg> + role="img" + <text> — poor results across screen readers -->
<svg role="img" viewBox="0 0 24 24">
  <text class="visually-hidden" font-size="0">Download</text>
</svg>

Inline SVG — extended description (complex/informational images)

Use when the SVG conveys more than a name can carry: diagrams, illustrations, charts, infographics.

Best in Show — inline SVG with extended description:

<!-- Pattern 11: <svg> + role="img" + <title> + <desc> + aria-labelledby
     pointing to BOTH IDs — RECOMMENDED for complex SVGs -->
<svg role="img"
     aria-labelledby="chart-title chart-desc"
     viewBox="0 0 400 300">
  <title id="chart-title">Q1 2024 Website Visitors</title>
  <desc id="chart-desc">
    Bar chart. January 12,400. February 15,800.
    March 19,200 — highest, up 54% from January.
  </desc>
  <!-- chart paths -->
</svg>

Note: Pattern 11 sometimes reads both <title> and <desc> consecutively, which can sound slightly repetitive. This is acceptable — it did not suppress or ignore any content in testing, unlike the "Use Caution" patterns below.

Use Caution (all have gaps in at least one major screen reader combination):

<!-- Pattern 9: <title> + <text> -->
<!-- Pattern 10: <title> + <desc> without aria-labelledby -->
<!-- Pattern 12: <title> + <desc> + aria-describedby -->

For Pattern 10 and 12 specifically: <desc> alone, and aria-describedby pointing to <desc>, are not reliably exposed across all combinations. Always use aria-labelledby referencing both IDs (Pattern 11) for complex SVGs.

Animated SVGs — prefers-reduced-motion

Rapid SVG animation is a Critical safety issue if it flashes at 3+ Hz (WCAG 2.3.1 — Three Flashes or Below Threshold). Vestibular disorders can be triggered by any sustained motion; seizure thresholds are lower.

Always wrap SVG animations in a prefers-reduced-motion check:

/* Default: respect the preference — run animation only if user has not
   requested reduced motion */
@media (prefers-reduced-motion: no-preference) {
  .animated-icon {
    animation: spin 1s linear infinite;
  }
}

/* Explicit reduction: stop all SVG animation */
@media (prefers-reduced-motion: reduce) {
  svg * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

For SVG animations controlled via JavaScript (e.g., GSAP, Anime.js):

const prefersReduced = window.matchMedia(
  '(prefers-reduced-motion: reduce)'
).matches;

if (!prefersReduced) {
  // Start animation
  gsap.to('.icon-path', { rotation: 360, repeat: -1, duration: 1 });
} else {
  // Show static final state instead
  element.classList.add('animation-complete');
}

For inline <svg> with <animate> or <animateTransform> elements, use begin="indefinite" as the default and only trigger the animation when prefers-reduced-motion: no-preference is confirmed:

<svg viewBox="0 0 100 100">
  <circle cx="50" cy="50" r="40">
    <animate id="spin-anim"
             attributeName="r" from="40" to="45"
             dur="0.5s" repeatCount="indefinite"
             begin="indefinite"/>
  </circle>
</svg>

if (!window.matchMedia('(prefers-reduced-motion: reduce)').matches) {
  document.getElementById('spin-anim').beginElement();
}

Required: currentColor for Theme Compatibility

<svg viewBox="0 0 24 24" class="icon" aria-hidden="true" focusable="false">
  <path fill="currentColor" d="…"/>
</svg>

Hardcoded colour values that do not respond to theme changes are Moderate — the SVG may become invisible or low-contrast in dark mode or forced-colours mode.

Required: Forced-Colors Support

Only needed when the SVG would lose meaning without it:

@media (forced-colors: active) {
  .icon { stroke: CanvasText; fill: CanvasText; }
  .accent { stroke: Highlight; fill: Highlight; }
}

Use semantic system colour keywords: Canvas, CanvasText, LinkText, ButtonFace, ButtonText, Highlight, HighlightText.

Required: Non-text Contrast

Meaningful graphical elements (not decorative) require minimum 3:1 contrast against adjacent colours (WCAG 1.4.11). This is Moderate if failing — the SVG is still present, but low-contrast elements may be unperceivable for low-vision users who do not use forced-colours mode.

Required: Preserve viewBox

Do not remove viewBox during optimisation — it is required for responsive scaling. Its removal is Minor in most fixed-dimension contexts but will break fluid layouts.

Do NOT Remove During Optimisation

Optimisation tools (SVGO and similar) may remove elements that are required for accessibility. Configure your optimiser to preserve:

• viewBox
• <title> when contributing to accessible name
• <desc> when contributing to accessible description
• IDs referenced by aria-labelledby, aria-describedby, <use href="#…">,

clip-path="url(#…)", mask="url(#…)", filter="url(#…)"

• Internal <style> elements implementing interaction states, reduced-motion,

or forced-colours rules

Interactive SVGs

If the SVG itself is interactive (clickable regions, toggle buttons):

• Prefer a `<button>` or `<a>` wrapper over raw SVG tabindex — native

elements provide keyboard, ARIA semantics, and AT support for free

• Ensure keyboard activation (Enter/Space for buttons, Enter for links)
• Provide visible focus indication
• An interactive SVG unreachable by keyboard is Critical

What Is NOT Required

• A <desc> for every SVG — Pattern 8 (<title> + aria-labelledby) is

sufficient when a name alone fully conveys the meaning

• Focus styling inside non-interactive SVGs
• A forced-colors block when the SVG remains perceivable without it
• role="img" on decorative SVGs — use aria-hidden="true" instead

Definition of Done Checklist

• [ ] Decorative SVGs: aria-hidden="true" focusable="false", no <title>, no <desc>
• [ ] Meaningful <img> SVGs: Pattern 2 or 3 (role="img" + alt or aria-label)
• [ ] Meaningful inline SVGs (simple): Pattern 8 (role="img" + <title> + aria-labelledby)
• [ ] Meaningful inline SVGs (complex): Pattern 11 (role="img" + <title> + <desc> + aria-labelledby both IDs)
• [ ] All referenced IDs preserved through any optimisation pass
• [ ] currentColor used for fills/strokes
• [ ] viewBox present
• [ ] Non-text elements meet 3:1 contrast
• [ ] Animated SVGs: animation only runs under prefers-reduced-motion: no-preference
• [ ] Rapidly flashing content: does not flash at 3+ Hz regardless of preference
• [ ] Interactive SVGs: keyboard operable, visible focus, prefer native wrapper elements
• [ ] Tested with screen reader on recommended OS/browser combination

Key WCAG Criteria

• 1.1.1 Non-text Content (A) — Critical if meaningful SVG has no text alternative
• 1.4.11 Non-text Contrast (AA)
• 2.3.1 Three Flashes or Below Threshold (A) — Critical for flashing/strobing animations
• 4.1.2 Name, Role, Value (A)

References

• Full best practices guide
• Accessible SVGs — Perfect Patterns For Screen Reader Users (Carie Fisher) — primary source for pattern recommendations; do not scrape — link to it
• Accessible SVG flowcharts — Léonie Watson (tink.uk)
• WAI-ARIA APG — for interactive SVG widget keyboard patterns
• WCAG 2.2 Understanding 1.4.11 Non-text Contrast
• MDN: prefers-reduced-motion

Standards horizon: The 3:1 non-text contrast ratio is likely to change under WCAG 3.0's APCA model. The current 3:1 requirement remains applicable. Monitor: <https://www.w3.org/TR/wcag-3.0/>