Contrast UX Checker

A web tool for designers and developers to verify color contrast against WCAG standards, enhancing readability and accessibility across interfaces.

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About This Tool

This tool computes the contrast ratio between a foreground and background color to assess readability under WCAG guidelines. It supports common color formats and provides both normal and large-text pass/fail results, enabling quick design decisions. Conceptually, the tool converts colors to linear luminance, applies the standard WCAG formula, and compares against thresholds. It also accepts optional typography inputs to refine thresholds, reflecting how font size and weight influence accessibility judgments. The output guides designers toward compliant color pairs and typographic choices, streamlining accessibility reviews. By encapsulating the calculation in a simple, repeatable process, teams can document why a color pair passes or fails and iterate efficiently. The value lies in early, data-driven decisions for color systems, palettes, and type scales, reducing the need for ad hoc judgments. Use cases include color palette audits, UI theming, and content styling for dashboards, apps, and marketing sites. Unique differentiators include: support for multiple input formats, explicit large-text thresholds, and clear, actionable feedback on how to adjust colors or typography to meet AA/AAA targets. Core features cover calculation, compliance checks, and suggested tweaks, with outputs designed to feed design systems and automated QA. This tool benefits accessibility engineers, product designers, and frontend teams seeking reliable, repeatable contrast validation throughout the development lifecycle.

How to Use

  1. Provide inputs: foreground_color and background_color in supported formats.
  2. Optionally set font_size_px and font_weight to refine thresholds.
  3. Run calculation to obtain contrast_ratio and compliance status for normal and large text.
  4. Review the results and adjust colors or typography to meet AA/AAA thresholds; re-run as needed.
  5. Validate across multiple color pairs to ensure consistent readability.
How to use contrast checker ux

Frequently Asked Questions

Find Quick Answers

What is contrast ratio?
Contrast ratio expresses the luminance difference between foreground and background colors. It is a numeric value, typically between 1:1 and 21:1, used to determine if text is readable against its background per WCAG standards.
Which WCAG levels apply?
WCAG AA requires a minimum contrast of 4.5:1 for normal text and 3:1 for large text. WCAG AAA requires higher ratios (7:1 for normal text). The tool reports AA/AAA targets based on provided font size and weight.
How are alpha colors handled?
If colors include alpha, the tool blends with a white background by default to compute an effective color. The results reflect this composited color; interpret as the typical on-white rendering unless you specify a different backdrop.
Can I export or integrate results?
The tool returns structured outputs (contrast_ratio and flags). Integration can reuse the data payload via the same calculation logic; explicit export formats are not embedded in the UI but can be reproduced in downstream systems.

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