One of the most common issues I see when testing is the content not having enough contrast. With 1.4.3, we’re focus on the contrast of text. This can be text in an image or just on the page. Later we’ll talk about the contrast of active controls in 1.4.11.
Designers commonly complain that they can’t design with the restrictions that WCAG has in place for contrast. At the same time the great designers love restrictions. So your reception will vary when you work with a designer. Remember, they don’t get a choice about adhering to the contrast levels set out.
Defining Contrast
Outlined in WCAG, we have two contrast levels we need to look out for text. We divide text into “normal” or “body” text and “large” text. Body text is all text smaller than 18 point and not bold. If it is bold, it can be as small as 14 point. Everything bigger than that is large text.
This is body text at 14 point.
This is large text, bold at 14 point.
This is large text at 18 point.
1 point does not equal 1 pixel.
1 point is actually 1.3 CSS pixels.
If you are like me, you are looking at those blocks thinking that they don’t look like 14 and 18 pixels. Heck, this body text looks the same size as the 18 point. Well that is because I use a larger than normal font for easier reading. Additionally, 1 point does not equal 1 pixel. 1 point is actually 1.3 CSS pixels. This means 14 point is really 19 rendered pixels. Eighteen point comes out to 24 pixels.
How do we determine what size it is?
In Chrome and Firefox, the web inspector tools offer a “Computed” section. After highlighting the element in the code, switch to the computed tab and look for font-size. This will show the rendered pixel height regardless of what measurement you used to set the size. In addition to points, font sizes can be set with EM, REM, pixel, percentage, viewport height and width, just to name the most common.
What are the contrast levels?
Now that we know how to measure our fonts, let’s look at the contrast levels. We have two remember. One for body text and one for large text. For body text, the contrast ratio is 4.5:1. For large text the contrast ratio is 3:1. There are many contrast checkers on the market, so feel free to find one and use it.
My personal favorite is Level Access’s Accessible Color Picker for Chrome. Full disclosure, I currently work for Level Access. However, I’m not pitching the company. This color contrast tester not only provides the contrast and if it passes A, AA, or AAA, but is also helps guide you to fixing the colors.
On the side of the contrast values is a five by five grid. Your picked colors are in the middle. If you move up or down in the grid, options are shown for your background. Moving left or right in the grid changes the foreground. These options may have better contrast.
As a developer using this tool, I look for contrast pairs that don’t work. When I find an issue, I will suggest a color combo from these suggestions that does work. Then the designer just needs to approve, moving the process forward.
What is APCA?
The WCAG is imperfect. It is a volunteer organization of hundreds trying their best to develop accessible rules the majority can agree on. On of the flaws is in the algorithm for finding contrast. There are combos that fall below WCAG standards that are no issue for people with color blindness. There are also combos that meet the criteria, but are unusable because they irritate eyes.
When the efforts to bring WCAG to the next level beyond 2.2, those involved began investigating other contrast algorithms. APCA is one of those. It looks like it will be how we evaluate contrast in the future. However, if you are building a website today it doesn’t matter. The current rules and laws all point back to WCAG 2.x and the algorithm used in that is not APCA. To comply with the current law, you must test colors under the current algorithm. This is true even if you use APCA to choose your colors. If you can use combos that pass both, you are future protecting yourself.
Have questions on this topic? Find me on LinkedIn and BlueSky to chat!