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WCAG 1.4.12 Text Spacing Override Tester

Users with dyslexia or low vision override text spacing. If your layout clips or overlaps under those overrides, it fails WCAG 1.4.12. This tool applies the exact four metrics and shows you what breaks — side by side with the default.

Web Accessibility Local processing Your code stays in your browser. Nothing is uploaded.

Tool interface

Introduction

WCAG 1.4.12 requires that no loss of content or functionality occurs when users apply specific text-spacing overrides. This tool reproduces those overrides and surfaces clipping so you can fix it.

How it works

  • Renders default and overridden previews in sandboxed iframes.
  • Injects the selected WCAG spacing metrics with !important.
  • Scans the overridden document for elements whose scroll size exceeds their client size under a clipping overflow.
  • Lists each clipped element with its selector.

Privacy

All rendering and measurement is local. No upload, no account, no API key.

Limitations

  • Detects clipping via scroll/client size; absolute-position overlap needs manual review.
  • Sandboxed preview blocks scripts in your snippet.

FAQ

What are the exact WCAG 1.4.12 metrics?

Line height 1.5, letter spacing 0.12em, word spacing 0.16em, paragraph margin-bottom 2em.

Is my code uploaded?

No. Everything runs locally.

Related tools

Version and changelog

  • Version: 1.0.0
  • Last updated: August 12, 2026
  • Changelog: Initial production release.