From an accessibility standpoint, that’s often not enough to catch real compliance issues.
The Accessibility Standard Behind This
Under ADA Title II, public entities are expected to meet WCAG 2.1 Level AA. While WCAG doesn’t prescribe exact testing steps for mobile devices, it does define outcomes that must be met.
Two WCAG success criteria are especially relevant here.
When accessibility testing comes up, mobile devices are often mentioned—but the testing itself usually stops too early.
A common pattern we see is testing a site on mobile at 100% zoom, confirming it looks fine, and moving on.
From an accessibility standpoint, that’s often not enough to catch real compliance issues.
WCAG 1.4.4 — Resize Text
Requirement:
Text must remain readable and functional when resized up to 200%, without loss of content or functionality.
On desktop systems, this is commonly tested using browser zoom or text-only zoom. On mobile devices, text resizing is typically achieved through system font size settings or browser text scaling rather than pinch-to-zoom.
While pinch-to-zoom magnifies the entire page, it does not cause text to reflow and is not the primary method WCAG relies on to evaluate text resizing.
However, zooming interactions on mobile can still expose underlying layout weaknesses. If increasing text size or effective zoom causes:
- Text overlapping or truncation
- Buttons or links becoming hidden or unreachable
- Navigation controls breaking or disappearing
…the page may fail WCAG 1.4.4, regardless of how the issue is discovered.
WCAG 1.4.10 — Reflow
Requirement:
Content must reflow without requiring horizontal scrolling when viewed at increased text sizes or narrow viewport widths.
This criterion is often tested at 400% zoom on desktop, which effectively simulates a narrow viewport similar to a mobile device with enlarged text.
On mobile devices, this means layouts must adapt when:
- Text size is increased via OS or browser settings
- The viewport is constrained to ~320 CSS pixels wide
If these conditions cause:
- Horizontal scrolling
- Fixed-width elements that break layout
- Controls or content moving off-screen
…the page may fail WCAG 1.4.10, even if it appears fine at default settings.
How to Test This in Practice (Mobile)
A practical mobile accessibility check goes beyond simply viewing the site at default size.
Recommended steps:
- Open the site on a mobile device
- Review it at normal (100%) settings
- Increase system or browser text size (or simulate equivalent zoom on desktop)
- Verify that:
- Text remains readable
- Navigation and controls remain usable
- Content reflows without horizontal scrolling
- No information is lost or clipped
Pinch-to-zoom can be used as an exploratory aid, but it should not be the sole basis for determining WCAG compliance.
Why This Matters for Real Users
Many users with low vision rely on larger text sizes rather than visual magnification. When layouts fail to reflow or content becomes inaccessible at increased text sizes, those users may be unable to:
- Read announcements or schedules
- Complete forms
- Use navigation menus
- Access contact or support information
From an accessibility standpoint, a site that fails under these conditions may be effectively unusable.
A Common Oversight (Including Ours)
Like many teams, we historically evaluated mobile layouts primarily at default settings. Closer attention to text resizing and reflow reveals issues that automated scans and surface-level checks often miss.
Accessibility isn’t just about whether a page loads or looks correct at first glance — it’s about whether content remains usable when users interact with it in ways that meet their needs.
Try This Today
If you’re responsible for a website, try this quick check:
- Open your site on a mobile device
- Increase text size via system or browser settings
- Navigate through key pages, menus, and forms
If content becomes unreadable, overlaps, or requires horizontal scrolling, it’s a strong indicator that accessibility improvements are needed — particularly around text resizing and responsive layout behavior.
