The Color Contrast Checker is an interactive, free, and ad-free online tool that assesses color contrast for digital accessibility. It adheres to the contrast criteria set by the Web Content Accessibility Guidelines (WCAG) at AA and AAA levels.
Digital accessibility requires sufficient contrast and appropriate font sizes to ensure optimal readability. This tool calculates contrast ratios and visualizes them with colors and fonts, making it easy to determine suitable color combinations for design.
Check Color Contrast for Digital Accessibility
- The contrast calculator requires two color inputs: foreground color and background color. Supported formats include
HEX,RGB, andHSL. - The calculator determines the contrast ratio and verifies its compliance with WCAG AA and AAA standards for normal and large text.
- Below this, a visual representation of the selected color combination and text size is provided.
Accessibility
Legal requirements such as the Web Content Accessibility Guidelines (WCAG) (external link) and the European Accessibility Act (Directive 2019/882) (external link) are key factors in assessing sufficient contrast in color and size.
These regulations are based on WCAG standards (levels A and AA). This tool checks compliance and also evaluates whether higher AAA requirements are met. More about liability.
Why Accessibility Matters
Beyond legal obligations, adequate contrast promotes inclusivity and accessibility for everyone. Ensuring clear color differentiation in designs improves usability and enhances the user experience.
A well-designed, accessible website can:
- Increase traffic
- Expand audience reach
- Improve usability
However, WCAG contrast standards may appear complex at first. Many designers are unaware of the necessary adjustments required for compliance.
WCAG Minimum Contrast Requirements
The WCAG 2.1 and 2.2 guidelines define specific contrast and size ratios to ensure better readability for people with visual impairments or color blindness. These requirements fall under the “Perceivable” principle, ensuring clear text and visual distinctions.
- Text Contrast (Minimum) – Success Criterion 1.4.3
The ratio of text and text images to their background should be at least4.5:1to ensure legibility for people with visual impairments. This applies to normal text. For large text (from 18 point or 14 point bold), a ratio of at least3:1is considered sufficient. - Graphics & UI Elements – Success Criterion 1.4.11
The visual information required to understand content or operate user interface elements must also have a minimum contrast ratio of3:1against the adjacent colors. This also applies to interactive elements such as buttons and form fields. - Text in Images – Success Criterion 1.4.5
Text embedded in images should be avoided, as it often fails contrast standards and lacks scalability. Where unavoidable, a minimum contrast ratio of4.5:1must be maintained.
Contrast Calculation
Contrast is a key factor in visual perception, referring to the difference in brightness or color that allows objects to be distinguished. This is measured based on luminance levels.
Contrast Types
- Weber Contrast – Measures the contrast between an object and its background. Useful for traffic signs, displays, and real-world visibility.
- Michelson Contrast – Evaluates contrast in text, symbols, and patterns. Commonly used for screen readability and digital interfaces.
Both contrast types are essential for accessible design, particularly for users with visual impairments.
Automated Contrast Checking
Manual contrast calculations can be time-consuming. Our free contrast calculator allows for quick, precise measurements.
Polarity Effect: Light vs. Dark Mode
The polarity effect describes how background color affects readability:
- Positive Polarity (Dark text on light background – Light Mode): Generally better for readability, reducing eye strain.
- Negative Polarity (Light text on dark background – Dark Mode): Reduces glare in low-light environments.
Choosing the right polarity enhances user comfort and accessibility.
Frequently Asked Questions (FAQ) about Contrast
Contrast (Italian contrasto ‘opposite’ and Latin contra ‘against’ and stare ‘to stand’) generally means opposition or clear difference.
This website is not about linguistic/semantic differences, but about visual/color differences – i.e. the difference between light and dark colors.
A good contrast ratio depends on the intended use. On digital monitors, the Web Content Accessibility Guidelines (WCAG) recommend a minimum of 4.5:1 for normal-sized text (14 point) and at least 3:1 for large text (18 point). This ratio ensures that texts are also sufficiently easy to perceive and read for people with visual impairments and visual limitations.
The ideal contrast ratio is high enough to ensure legibility and visibility without being unpleasant to the eye. This is because very strong contrasts such as black on white (21:1) can be unpleasant, especially digitally. This website usually has a contrast ratio of 16:1 in bright mode and is therefore close to the visually pleasant upper limit.
A contrast ratio of at least 4.5:1 is considered to be minimally sufficient, especially for text on a digital background.
The strongest contrast is achieved by pure white on pure black or vice versa, resulting in a contrast ratio of theoretically infinite. Calculated purely for digital monitors, this is 21:1.
This theoretically maximizes visibility, but in practice is perceived as too intense and unpleasant. Ultimately, this also depends on the monitor used and its settings in each individual case.
An accessible contrast is based on the legal regulations. These differ, but are ultimately based on the WCAG requirements for contrast. This means at least a ratio of 4.5:1 for normal text (14 point) and 3:1 for large text (18 point) or graphic elements to make it easier for users with visual impairments to use.
Beyond Color Contrast: Additional Accessibility Factors
Besides contrast, typography plays a key role in readability. Consider:
- Font: Characters must be recognizable and distinguishable, line weight contrasts also play a role here.
- Character spacing, spacing: give more character spacing, especially for capitals (capital letters), even for light text on a dark background.
- Emphasis: use short headings, paragraphs, bold, italics, markings sparingly and selectively.
- Line spacing: the longer the lines, the more spacing – readability before appearance.
- Line length: depending on the type of text, between 35 and 80 characters (including spaces) per line are recommended.
- Alignment: justified text in particular is irregular, large spaces between words are more difficult to read and should be avoided on the web.
Topics Covered in This Guide
#colorcontrast #Accessibility #accessible #WCAG #contrast #check #tool #calculate #comparison #preview #Readability #UX
Questions, Issues, or Suggestions?
Have feedback or found a bug? We’d love to hear from you: mail@color-contrast-checker.com (to the contact details).
Liability Disclaimer
While extensive checks are performed, we cannot guarantee full legal compliance with contrast regulations in every case.
Changelog, Release Notes
- 18.02.2025
Visual improvements to user-friendliness. - 17.02.2025
Initial version of the contrast calculator tool.
Sources & Further Reading
- https://www.w3.org/TR/WCAG22/ (external link), last accessed on 02-17-2025.
- https://www.w3.org/WAI/WCAG22/Understanding/contrast-minimum.html (external link), last accessed on 02-17-2025.
- https://www.siteimprove.com/de/toolkit/color-contrast-checker/ (external link), last accessed on 02-18-2025.
- https://en.wikipedia.org/wiki/Color_analysis (external link), last accessed on 02-17-2025.
- https://chromewebstore.google.com/detail/color-contrast-checker/kmjlkobpbcgeflclpglpiocncbknmacj (external link), last accessed on 06-14-2025.