Readable text size on mobile: Crawl Audit check 105

Short answer: body text that's too small makes people squint, pinch and leave. Check 105 warns when the font sizes written into your HTML are all under 15 pixels. It's a rough test: it only sees sizes set inline, not in your stylesheets, so most sites pass.

What Crawl Audit checks

• Crawl Audit collects font-size values in pixels from the HTML, between 8 and 24 pixels.
• Pass: none found, or at least one is 15 pixels or more.
• Warning: all of them are under 15. The advice says to use at least 16 pixels for body text.

What the sources say

There's no single official minimum:

• WCAG doesn't set a minimum font size. It requires that text can be enlarged to 200% (check 102).
• Lighthouse used to flag pages where "40% or more of the text has a font size smaller than 12 px". It removed that audit in version 13, saying "there are no signals that this remains an SEO concern today".
• Google's Material Design uses 14 as its base body size. Apple's default text size on iPhone is 17 points.

The 16 pixel advice is ours, a common and safe default. It's the browsers' default text size, and close to the Apple figure above.

How to fix it

html { font-size: 100%; }  /* the browser default, 16px for most people */
body { font-size: 1rem; line-height: 1.5; }

• Set body text in rem so it follows the visitor's own browser setting.
• Keep small text for captions and labels, not paragraphs.
• Check on a real phone at arm's length.

Sources

• W3C, Understanding 1.4.4 Resize Text, checked 6 October 2026.
• Chrome for Developers, Document doesn't use legible font sizes and What's new in Lighthouse 13 (10 October 2025).
• Material Design, Type scale tokens; Apple, Accessibility.