Look around your website. How much of the information on the screen depends on color? A red “Error” message. A green “Available” badge. A chart where each data series is a different hue. A button that turns blue when active. If you removed every color from the page, would the meaning still be clear?

For millions of users, this is not a thought experiment. It is their everyday experience.

Color blindness affects approximately 1 in 12 men (8%) and 1 in 200 women (0.5%) worldwide. That translates to roughly 300 million people globally who see the world differently than most designers do. If your website relies on color alone to communicate meaning, a significant portion of your audience is locked out of that information.

The good news is that designing for color blindness is not difficult once you understand the problem. In this guide, we will cover what color blindness actually is, how it affects web use, and the specific design changes you can make today to ensure your site works for everyone.

What Is Color Blindness?

Color blindness, more accurately called color vision deficiency, is a reduced ability to distinguish between certain colors. It is almost always inherited, though it can also result from eye disease, medication side effects, or aging.

The retina contains two types of light-sensitive cells: rods (which handle low-light vision) and cones (which handle color vision). There are three types of cones, each sensitive to a different range of light wavelengths: roughly red, green, and blue. Color blindness occurs when one or more of these cone types is missing or does not function normally.

The Main Types of Color Vision Deficiency

Red-Green Color Blindness (Most Common)

This is by far the most common category. It comes in several forms:

  • Deuteranomaly is the most common type overall. It affects the green-sensitive cones, making green look more red. It affects about 5% of men.
  • Protanomaly affects the red-sensitive cones, making red look more green and less bright. It affects about 1% of men.
  • Protanopia and deuteranopia are more severe forms where the red or green cones are completely absent. People with these conditions see red and green as the same basic shade.

Blue-Yellow Color Blindness (Less Common)

  • Tritanomaly affects the blue-sensitive cones, making blue look more green and yellow look more red. It is rare and often acquired later in life.
  • Tritanopia is the complete absence of blue-sensitive cones. Blue appears green, and yellow appears pink or red.

Complete Color Blindness (Rare)

  • Achromatopsia (monochromacy) is a rare condition where people see no color at all. The world appears in shades of gray. It affects approximately 1 in 30,000 people.

For web design purposes, the most important thing to understand is that red-green deficiencies are by far the most common. If you design with red-green color blindness in mind, you will address the vast majority of color vision issues your users face.

How Color Blindness Affects Web Use

Color vision deficiencies create specific problems on the web. Here are the most common barriers:

1. Status Indicators That Rely on Color Alone

A form field that turns red when invalid and green when valid is a classic example. For a user with red-green color blindness, both colors may look like the same muted brownish shade. They cannot tell whether their input was accepted or rejected.

2. Charts and Data Visualizations

Charts that use color to distinguish data series are a major barrier. A pie chart with red, green, and brown slices is essentially unreadable for someone with deuteranopia. The slices all look the same.

Some websites style links with a slightly different color from body text but no underline. For users with color vision deficiencies, the link color difference may be invisible. They cannot tell which text is clickable.

4. Required Form Fields

If a red asterisk indicates a required field, a user with protanopia may not see the asterisk as different from black text. They might skip the field entirely and encounter an error on submission.

5. Error and Success Messages

“Your changes have been saved” in green and “There was a problem” in red are common patterns. Without an icon or text label to distinguish them, color alone may not communicate the message type.

6. Navigation and Interface States

Active tabs, selected items, and hover states that only use color changes are invisible to many color blind users. They cannot tell which tab is active or which item they have selected.

The WCAG Requirements for Color

The Web Content Accessibility Guidelines (WCAG) address color reliance directly. Two success criteria are particularly relevant:

WCAG 1.4.1: Use of Color (Level A)

This is the core requirement. It states: “Color is not used as the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element.”

In practice, this means:

  • If you use color to indicate an error, also include a text message or an icon.
  • If you use color to mark required fields, also use a text label like “(required)” or a non-color symbol.
  • If you use color to show which navigation tab is active, also use a visual indicator like an underline, a border, or a different font weight.
  • If you use color in a chart, also use patterns, labels, or direct text annotations.

This is a Level A requirement, which is the minimum standard for accessibility. If your site fails this criterion, it is not accessible.

WCAG 1.4.3: Contrast (Minimum) (Level AA)

While not specific to color blindness, contrast requirements matter because some color vision deficiencies reduce the perceived contrast between elements. Text must have a contrast ratio of at least 4.5:1 against its background (3:1 for large text). Learn more about WCAG compliance levels and how they apply to your site.

WCAG 1.4.11: Non-Text Contrast (Level AA)

User interface components and graphical objects must have a contrast ratio of at least 3:1 against adjacent colors. This applies to form field borders, button outlines, focus indicators, and chart elements.

Practical Design Strategies for Color Blindness Accessibility

1. Never Use Color Alone to Convey Meaning

This is the single most important rule. Every piece of information communicated by color must also be communicated another way. Here are some specific examples:

Form validation:

  • Bad: The field border turns red on error.
  • Good: The field border turns red AND an error icon appears AND a text message says “Please enter a valid email address.”

Status badges:

  • Bad: Green dot means “online,” red dot means “offline.”
  • Good: Green dot with a checkmark icon means “online,” red dot with an X icon means “offline.” Or better yet, include the text “Online” or “Offline” next to the dot.

Required fields:

  • Bad: Red asterisk next to the field label.
  • Good: The word “(required)” in text next to the field label. Or an asterisk with a legend at the top of the form that says “* Required field” in the same font weight as the labels.

Links in body text:

  • Bad: Links are a slightly different shade of blue from the body text.
  • Good: Links are underlined or have a distinct visual treatment beyond color alone, such as a bold font weight.

2. Use Textures and Patterns in Charts

For data visualizations, color should never be the only way to distinguish data series. Use these techniques:

  • Add patterns or textures. Instead of solid colors, use diagonal stripes, dots, or crosshatch patterns for each data series. Tools like Chart.js and D3.js support pattern fills.
  • Label data directly. Place text labels on or near each data point rather than relying solely on a color-coded legend.
  • Use varying brightness. Instead of red and green (which can look identical to color blind users), use light blue and dark blue. Different brightness levels are easier to distinguish than different hues.
  • Provide a data table. Always offer a text-based alternative to visual charts. A data table ensures that users who cannot interpret the chart can still access the underlying information.

3. Choose Color Blind Friendly Palettes

Some color combinations are notoriously difficult for color blind users:

  • Red and green (the most common problem pair)
  • Green and brown
  • Blue and purple
  • Green and blue
  • Light green and yellow

Instead, use combinations that are distinguishable regardless of color vision type:

  • Blue and orange is widely considered the most universally distinguishable color pair.
  • Dark blue and bright yellow provides strong contrast for most types of color blindness.
  • Purple and yellow are complementary and remain distinct for most users.

Several tools can help you design color blind friendly palettes. Coblis lets you upload an image and see how it looks under different types of color blindness. ColorBrewer offers color schemes specifically designed to be safe for color blind users.

4. Test Your Designs With Simulators

You do not need to have color blindness to design for it. Simulators let you see your designs through different color vision types. Here are some options:

  • Browser extensions: The Chrome extension “Spectrum” simulates color blindness on any web page in real time.
  • Design tools: Adobe Photoshop and Figma have built-in color blindness preview modes.
  • Online simulators: Upload a screenshot to see how it looks to users with different color vision deficiencies.
  • Standalone tools: Stark is a suite of accessibility tools that includes color blindness simulation for Figma, Sketch, and Adobe XD.

Make it a habit to run every new design through a simulator before shipping it. A quick check can catch problems you would never notice otherwise.

5. Provide Clear Focus Indicators

Focus indicators help keyboard users know which element they are currently on. Color alone is not enough. WCAG 2.4.7 (Focus Visible) requires that keyboard focus be visually visible. Use a combination of:

  • A contrasting outline (at least 3:1 ratio against the background)
  • A thickness of at least 2 pixels
  • A shape change (such as an underline or border) in addition to color

For more on keyboard accessibility, see our guide to using ARIA for web accessibility, which covers focus management in detail.

6. Write Descriptive Alt Text

Images that use color to convey information need descriptive alt text. For example, a map that uses red to show high-risk areas and green to show low-risk areas should have alt text like: “Map showing high-risk areas in red and low-risk areas in green.” Even better, provide the information in a text format alongside the image so users do not need to interpret the color coding at all.

Learn more in our guide on making media accessible, which covers alt text and other media accessibility principles.

7. Design Buttons and Interactive Elements With Multiple Cues

A button should be recognizable as a button even without color. Use these cues:

  • A visible border or outline
  • A distinct shape (rounded corners, shadow, or elevation)
  • Text that clearly describes the action
  • Hover and active states that change more than just color (such as a shadow change or slight scale)

8. Use High Contrast for Text on Colored Backgrounds

Text on colored backgrounds is particularly tricky for color blind users because the perceived contrast may be lower than you think. A red button with white text that looks fine to you might look like a muddy brown button with low-contrast text to someone with protanopia. Always test text on colored backgrounds with a contrast checker and a color blindness simulator.

Common Mistakes to Avoid

Relying on Color Coded Alerts Without Text

Many websites use a colored banner (red for error, green for success, yellow for warning) without an icon or text label. For color blind users, all three banners may look the same. Always include an icon and a text heading inside the banner.

Using Only Color to Show Selected Items

In a list of selectable items, highlighting the selected one with a background color is common. But if the color difference is subtle, color blind users will not know which item is selected. Add a checkmark icon or a “Selected” text label.

Designing With Red and Green Side by Side

Red and green are the most commonly confused colors. Avoid using them next to each other for different actions or data points. If you must use both, add icons or text labels to differentiate them.

Assuming High Contrast Means Color Blind Safe

Two colors can have excellent contrast for users with normal vision but be indistinguishable for color blind users. For example, a bright red and a bright green may both appear as the same shade of yellowish-brown to someone with deuteranopia. Contrast and color distinguishability are separate concerns. Address both.

Forgetting About Color in CSS

Inline styles and CSS that change element colors dynamically (such as form validation states) need the same treatment as any other color-based design. If your CSS adds a red border on error, also add an error icon or text message via the same CSS logic.

How to Audit Your Site for Color Accessibility

Testing for color blindness accessibility involves both automated and manual steps:

  1. Run an automated scan. Accessibility testing tools can catch contrast issues and some color-only information problems. Accessible Metrics scans your site against WCAG criteria including 1.4.1 (Use of Color) and 1.4.3 (Contrast Minimum).

  2. Use a color blindness simulator. Take screenshots of your key pages (homepage, checkout, forms, dashboard) and view them through a simulator. Look for any place where information is lost or hard to distinguish.

  3. Print pages in black and white. A quick and dirty test is to print your page or view it in grayscale mode. If any information disappears without color, you have a problem.

  4. Review charts and data visualizations. Go through every chart on your site. Can each data series be identified without color? If not, add patterns, labels, or a data table.

  5. Check form validation. Submit a form with errors. Is the error communicated through more than just color? Is the success state communicated through more than just color?

  6. Test navigation states. Click through your navigation. Can you tell which tab or page is active without relying on color alone?

For a broader look at testing methodology, see our guide on how to test the accessibility of your website.

The Business Case for Color Accessibility

Designing for color blindness is not just about compliance. It is about reaching more users and providing a better experience for everyone.

Consider these facts:

  • 8% of men have some form of color vision deficiency. If your audience skews male, that number could be even higher. You are potentially alienating a significant percentage of your visitors.
  • Color blind friendly designs tend to be clearer for everyone. Using text labels alongside colors, providing data tables alongside charts, and using high contrast all improve usability for users with typical vision too.
  • Accessible design reduces support costs. When users cannot complete tasks because of color-based barriers, they contact support or abandon the process entirely. Clear, multi-cue design reduces these friction points.
  • Legal compliance matters. WCAG 1.4.1 is a Level A requirement. Failing it means your site does not meet the minimum accessibility standard. Learn more about ADA compliance requirements and how they apply to your organization.

While this post focuses on color vision deficiencies, it is part of a broader picture. Low vision, cognitive disabilities, and other visual impairments all affect how users perceive and interact with your site. Good accessibility design addresses the full spectrum of visual differences.

For a comprehensive overview of accessibility issues, see our guide on the most common accessibility issues to avoid.

Getting Started

You do not need to redesign your entire site to make it more accessible for color blind users. Start with these quick wins:

  1. Add underlines to links in body text. This is a one-line CSS change that instantly improves link discoverability.
  2. Add text labels or icons to status indicators. If you use colored dots or badges, add a text label next to them.
  3. Check your forms. Make sure error states include text messages and icons, not just color changes.
  4. Review your charts. Add patterns or direct labels to any chart that relies on color to distinguish data.
  5. Run a simulator. Spend 10 minutes viewing your key pages through a color blindness simulator. You will likely spot issues you never noticed before.

Then run a full accessibility scan to catch the technical issues you may have missed. Accessible Metrics checks your site against WCAG 2.1 AA standards, including all color-related criteria. Every fix you make brings you closer to a site that truly works for everyone.

Ready to see how your site performs? Run a free accessibility scan with Accessible Metrics and get a detailed report against WCAG 2.1 AA standards, including color contrast and color usage issues that affect users with color vision deficiencies.