技術リファレンス&アーキテクチャガイド

WCAG Color Contrast Checker (AA & AAA Compliance) — リファレンスガイド

Test text and background color pairs against WCAG 2.1 AA and AAA accessibility standards with real-time contrast ratio score.

主要パラメータ&設定項目

Fg Inputstring

Configures fg input during client-side wcag color contrast checker (aa & aaa compliance) computation.

初期値: #F8FAFC
Bg Inputstring

Configures bg input during client-side wcag color contrast checker (aa & aaa compliance) computation.

初期値: #09090B
Preset Categorystring

Configures preset category during client-side wcag color contrast checker (aa & aaa compliance) computation.

初期値: All
Custom Textstring

Configures custom text during client-side wcag color contrast checker (aa & aaa compliance) computation.

初期値: Preset sample

プロの活用テクニック&推奨設定

Lightness Shade Spectrum Matrix

Explore all 10 lightness variants (10% to 95%) of the current text hue against your background. Click any shade to apply.

WCAG 2.1 AA vs. AAA Compliance

Level AA is the legally recognized international benchmark for web accessibility (ADA, Section 508, EN 301 549). It requires at least 4.5:1 for normal text and 3.0:1 for large text. Level AAA is enhanced accessibility ( 7.0:1 for body text), critical for public health, government, and high-glare environments.

Normal Text vs. Large Text Thresholds

WCAG defines Large Text as font sizes of at least 18pt (24px) for regular weight, or at least 14pt (18.66px) for bold weights (700+). Because larger glyphs feature thicker stroke weights, they remain readable at a lower contrast ratio of 3.0:1 .

よくあるトラブルと解決策

Unexpected output or validation warning in WCAG Color Contrast Checker (AA & AAA Compliance)

Verify that your fg input matches the expected string format. Load a built-in sample preset to compare structural formatting.

Exported wcag contrast checker result differs across target environments

Check the bg input setting in WCAG Color Contrast Checker (AA & AAA Compliance) to ensure encoding, precision, or specification version matches your target runtime.

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