WCAG AAA Text Size

WCAG AAA recommended text size

At the AAA level, WCAG 2.1 pushes the contrast ratio up to 7:1 for normal text. Large text (≥ 18pt regular or ≥ 14pt bold) gets a bit of slack at 4.5:1. To pick a font size, the practical rule is to scale with how far away the reader sits: size_pt ≈ distance_cm / 2.5. That keeps text readable for people with low vision.

A few related criteria matter here. Success Criterion 1.4.10 Reflow says content has to fit a 320 CSS pixel viewport without forcing horizontal scroll. 1.4.4 Resize Text wants text to enlarge up to 200% with nothing lost along the way. And SC 1.4.5 / 1.4.9 steers you away from text baked into images, logotypes being the one exception.

Applications

Think government portals, banking apps, healthcare dashboards, or anything chasing AAA conformance. It matters most when your audience includes older adults or low-vision users, or when the viewing distance keeps changing (TVs, kiosks, in-car displays). To check your work, lean on axe DevTools, Lighthouse, WAVE, and Pa11y.

FAQ

What is the minimum body text size on the web? WCAG never nails down a pixel number. In practice 16px (12pt) is where most people start, and designs aiming at AAA tend to push body copy to 18–20px.

Does zooming the browser satisfy 1.4.4? It can. As long as the layout, the controls, and the content all stay usable at 200% zoom with no horizontal scroll on a 1280px viewport, you've met the criterion.

How is contrast measured? It comes from the WCAG luminance formula (L1 + 0.05) / (L2 + 0.05), where L1 and L2 are the relative luminances of the foreground and the background.