Color Blindness Considerations for Designers and Content Managers

I recently read a Medium article on negative space published by a top design agency. The article had 5000 claps, so it was widely read. Unfortunately, the article’s primary example of good use of dark negative space was completely inaccessible to people who are color blind.

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Calendar app where background color is black and important actionable components are red. Good use of negative space, but red on black is almost invisible to people who are color blind
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Calendar app where background color is black and important actionable components are red. This is what someone with the most common form of color blindness sees. (Coblis Color blindness simulation)
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Paciello Group Colour Contrast Analyser results for the Calendar example above. For normal vision, the color choice barely passes at 3.1 (and even then only for large text) and fails across the board for the most common type of color blindness at 2.4

1 in 12 men have some form of color blindness (also referred to as Color Vision Deficiency or CVD) as do 1 in 200 women. That is 4.25 % of the population, which is a significant figure. McDonald’s serves 3 MILLION colorblind customers per day. Over 1.1 million of Amazon’s daily customers are colorblind.

It is completely unclear to me why designers think that it is acceptable to use colors (or combinations of colors) that others can’t see. This is a wide-spread problem that is very easily avoidable. The designers, who generally have unimpaired vision, think their color choices “look good.” However, if people who are color blind or older can’t see them, they are discriminatory. It’s also a ridiculously bad business practice — the whole purpose of thoughtful design is to ATTRACT users to your website / app over that of your competitors, not drive them away.

So what can designers do to avoid producing a design that makes 4.25 % of the population want to go to a competitors site / app?

Run all templates in the style guide through a color blindness simulation

Coblis is a drag-and-drop color blindness simulator. Take a screen shot of your style guide or comp, drop it into the simulation space and then play with the radio buttons to simulate what something looks like to people with various types of color blindness. Of the nine options provided by Coblis, Red-blind (aka Protanopia) and green-blind (aka Deuteranopia) are the most common types of color blindness.

The resulting image is how your design will appear to people with the form of color blindness you have selected.

· If it meets the relevant minimum color ratios, keep it.

· If someone with unimpaired vision has trouble seeing components or reading text, the design may benefit from tweaks either to the foreground or background colors to get better contrast.

Check what’s in production (currently) and re-check every time a content update is performed

· In WCAG 2.0, the color ratio minimums apply only to text.

· However, WCAG 2.1 extends the color guideline to activatable graphics and the keyboard focus indicator.

It doesn’t matter where the content comes from. Content provided by third-party partners must also meet the color ratio minimums.

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White text on light green background fails the WCAG color ratio minimums for all text sizes and compliance levels

Also, don’t forget to test the colors any time the text color changes. This most typically happens for hover states and visited links.

Don’t put hundreds of hours into making your site/app infrastructure accessible only to break it by allowing someone to update the content without making sure the new content meets the color ratio minimums.

Do a high contrast version of your site

Note that under the recent Scandinavian Airlines case, the default version of your site still needs to meet the minimum WCAG color ratio guidelines.

When implementing a high contrast version of a site:

· Make sure the “high contrast” link or icon is in the header or footer so it is available on every page.

· Make “high contrast” a single-click change that is continued once selected when viewing new pages on the same website

Never use color by itself to indicate importance or status

Icon with Alt-text

Appropriate alt text for these icons would depend on the circumstances. If there is enough information in the written text that makes identifying the graphics repetitive, these graphics could be considered decorative in which case alt should be set to null.


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4 lines each stating “emphasize this” with different forms of bold and underline styling


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Red box around placeholder text

Don’t use the following colors or color combinations

· Green on any dark color

· Red and green together

In addition to the above guidelines for color blindness, it is estimated that up to 30 % of people over the age of 65 cannot see silver, light gray, and pastels (especially blue and yellow)

· #949494 is the lightest gray usable for a large font and be WCAG compliant

· #767676 is the lightest gray usable for a small font and be WCAG compliant


Written by

Accessibility Architect @ VMware. W3C Silver, ITI & IAAP GLC committees. Degrees in CS, law, business. Wheelchair user w/ a deaf daughter.

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