WCAG 3.0 introduces a new contrast method

To ensure good readability, all text should have sufficient contrast against the background. This is important for all users, especially under challenging lighting conditions. Those who need this most are the visually impaired, dyslexics, and the color blind (source: uutilsynet).

Need for stricter contrast requirements

All users, including those with impaired vision, should be able to perceive content in digital services. The Web Content Accessibility Guidelines (WCAG) provide success criteria and recommended solutions. However, current contrast rules do not fully align with the goal of making content visible to everyone.

A new and more accurate method

WCAG 3.0 now proposes a more accurate method than today's standard for calculating contrast and setting threshold values.

• The method improves how the value between two colors is measured, and also differs based on whether the colors are in the foreground or background.

• It also sets clear threshold values or target values for font selection, text size, and font weight. The method is called Advanced Perceptual Contrast Algorithm (APCA).

• Our goal is to exceed AAA requirements in WCAG 2.1, witch means we will be closer to the threshold values in APCA. This increases the probability of meeting the requirement for everyone, including those with visual impairments, to be able to view the content on the website.

We follow a standard today that goes beyond the accessibility requirements

To ensure that the content in public digital services is accessible to all users, we aim to achieve compliance with WCAG 2.1 AAA.

To further enhance readability, we have ambitions to achieve contrast at level 4. This is the top level in the APCA method, which is now being proposed in WCAG 3.0.

Why isn't today's standard good enough?

We know that even if a solution meets the specific requirements from the universal design regulations, it is not necessarily universally designed and accessible. Since the eye's ability to perceive colors and light is not part of the method, it is unsuitable for calculating the difference in brightness in a combination of colors.

If we follow the method in WCAG 2, we technically meet the requirement for universal design, but this does not mean that the content is accessible or universally designed. Therefore, we will put in a lot of effort to also meet the future WCAG 3 requirements that use the APCA method.

Tools for testing contrast values

The Brønnøysund Register Centre's color system can be found in the contrast tool. You can test how contrast values change depending on which text color, size, and weight you choose. And you can see which levels of requirements are met, whether they are WCAG AA or AAA levels, or APCA.

The threshold values above that indicate whether the contrast is approved or not are simplified from an early "silver" level table from the APCA work. When a finished model has been tested and recommended from WCAG 3, the threshold values will be adjusted.

In the example above, we see that even though the contrast is calculated to be the same using the WCAG 2 method. The readability level differs for the texts in variant A and variant B. Both texts are 16px in normal weight, and both variants have a contrast of 4.6 to 1. In variant A, the text has the color #6D7879 with a white background. The text is somewhat readable. In variant B, the text is black, and the background has the color #6D7879. The text is slightly less readable than variant A.

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