The Web Content Accessibility Guidelines (WCAG), which are widely considered to be the international standards for digital accessibility, do not include set requirements for font size.
Of course, font size is important for accessibility — if people with vision disabilities cannot see your text, they can’t read it, either. But people view web content on a wide variety of devices. Generally, they have the ability to control the size of the text by adjusting their web browser settings or by using screen magnifiers.
The authors of WCAG understand that setting a minimum font size would not necessarily make the internet more accessible. Instead, WCAG has a requirement to ensure that people can control text size without losing functionality.
Here’s the full text of Success Criterion (SC) 1.4.4, “Resize Text:”
Except for captions and images of text, text can be resized without assistive technology up to 200 percent without loss of content or functionality.
In another article, we explained how to follow Success Criterion 1.4.4. You can learn more by reading: Give Yourself an Accessibility Test: Zoom Your Page to 200%.
But while WCAG is comprehensive, it doesn’t address every single issue that could make a website more or less accessible. Here are a few suggestions for setting default font sizes, along with additional tips for creating accessible, readable content.
A good rule of thumb: Try not to surprise your users with your web design decisions. Most text on the internet is around 16 pixels, equivalent to 12 points (pts) or 1 root em (rem). Wherever possible, you should keep your body fonts (the text that appears in paragraphs) to about that size or slightly larger.
Subheadings should be significantly larger than the body type. Remember, subheadings help your users understand your content and navigate your website. If subheadings are the same size as the body text, they’re much less useful.
When setting font styles in Cascading Style Sheets (CSS), don’t use absolute font sizes; use relative values (for example, rem instead of pts). Absolute type sizes can take control away from your users, which may violate WCAG’s requirements.
Related: Best Fonts To Use for Website Accessibility
According to an editorial published by JAMA Network Open, an estimated 1% of adults aged 50 to 54 years have a significant visual impairment or are blind. That number increases to more than 20% of people aged 85 years or older.
When content is geared towards older adults — or any other group that has a higher-than-average rate of vision disabilities — it makes sense to increase the default font size.
Where this is the case, Health Literacy Online recommends a font size of at least 19 pixels (14 pts or 1.669 rem). While you can rely on users to increase the font size on their own, remember that your goal is to deliver the best possible user experience. If you can avoid forcing your audience to change their browser settings, you should do so.
Related: The U.S. Population Is Aging. Is Your Website Accessible for Older Adults?
Font size is important, but there’s a reason that it’s not part of WCAG (at least, not at the time of writing). Other style decisions can create serious barriers for users:
You can avoid all these issues by following WCAG. Once you get into the habit of thinking about users with disabilities, you can make design decisions that improve user experiences — and start enjoying the benefits of accessible design.
To learn more about the best practices of digital accessibility, download our free eBook: Developing the Accessibility Mindset.