What is the minimum WCAG 2.1 contrast ratio for body text?

Under WCAG 2.1 Level AA, standard body text (< 18pt or < 24px) requires a minimum contrast ratio of 4.5:1 against its background. Level AAA requires at least 7.0:1.

What qualifies as 'Large Text' under accessibility guidelines?

Large text is defined as at least 18pt regular weight, or at least 14pt bold weight. Large text requires 3.0:1 for Level AA and 4.5:1 for Level AAA.

Does this tool work completely in my browser?

Yes. All sRGB linearizations, relative luminance formulas, and color deficiency matrix transformations execute 100% locally on your device without any external network calls.

Web Accessibility Suite

WCAG Color Contrast & Accessibility Checker

Q: What qualifies as 'Large Text' under accessibility guidelines?

Large text is defined as at least 18pt regular weight, or at least 14pt bold weight. Large text requires 3.0:1 for Level AA and 4.5:1 for Level AAA.

Q: Does this tool work completely in my browser?

Yes. All sRGB linearizations, relative luminance formulas, and color deficiency matrix transformations execute 100% locally on your device without any external network calls.

Verify WCAG 2.1 AA and AAA accessibility compliance, simulate color blindness vision, and auto-fix color pairs for accessible web design. 100% private in-browser tool.

Color Presets:

Text Color (Foreground)#0F172A

Background Color#FFFFFF

1-Click Auto-Fix Suggestions:

Computed Contrast Ratio

17.85:1

Meets highest Level AAA criteria

Interactive Preview

The quick brown fox jumps over the lazy dog. Sample body text rendering.

Normal Text AA< 18pt (Req. 4.5:1)PASS

Normal Text AAA< 18pt (Req. 7.0:1)PASS

Large Text AA≥ 18pt (Req. 3.0:1)PASS

Large Text AAA≥ 18pt (Req. 4.5:1)PASS

UI Components & IconsInputs, borders & graphics (Req. 3.0:1)PASS (AA Compliant)

Color Vision Deficiency (Color Blindness) Simulations

Protanopia (Red-Blind)

Aa 4.5:1

Deuteranopia (Green-Blind)

Aa 4.5:1

Tritanopia (Blue-Blind)

Aa 4.5:1

Achromatopsia (Grayscale)

Aa 4.5:1

WCAG 2.1 Contrast Standards & Font Thresholds

Element Type	Size Threshold	Level AA Minimum	Level AAA Enhanced
Normal Body Text	< 18pt (24px) regular	4.5:1 ratio	7.0:1 ratio
Large Headings	≥ 18pt (24px) or bold ≥ 14pt (18.66px)	3.0:1 ratio	4.5:1 ratio
UI Components	Inputs, radio buttons & icons	3.0:1 ratio	N/A (3.0:1 sufficient)

Common Web UI Color Pairs & Accessibility Grades

Combination	Foreground	Background	Contrast Ratio	Rating
Black on White	#000000	#FFFFFF	21.00:1	AAA Perfect
Slate 900 on White	#0F172A	#FFFFFF	16.32:1	AAA Pass
Indigo 600 on White	#4F46E5	#FFFFFF	5.91:1	AA Pass
Gray 400 on White	#9CA3AF	#FFFFFF	2.41:1	FAIL (Low Contrast)

How to Test and Fix Color Contrast Online

Pick Colors: Choose your foreground text color and background canvas color using hex codes or the color picker.
Inspect WCAG Compliance: Check the contrast score against AA (4.5:1) and AAA (7:1) guidelines.
Simulate Vision Deficiencies: Review protanopia, deuteranopia, and tritanopia cards to confirm your UI remains readable for all users.
Auto-Fix Contrast: If contrast fails, click "Auto-Fix to AA" to adjust the shade until it meets accessibility standards.

Frequently Asked Questions

100% In-Browser Privacy

All relative luminance calculations and color blindness simulation matrices execute locally on your device without any tracking or server uploads.

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