Accessible Font Size Calculator

Accessible font sizes (WCAG)

WCAG 2.1 level AA requires (1) contrast ratio ≥ 4.5:1 for normal text and ≥ 3:1 for large text (≥ 18px, or ≥ 14px bold); (2) zoom up to 200% without loss of content; (3) a body font of at least 16px as baseline good practice. Convert pixels to rem with rem = px / 16 (e.g. 18px = 1.125rem). WCAG 2.2 (2023) reinforced focus and target-size criteria. Material 3 and Apple's HIG suggest 17–18px for body. Older users benefit from larger sizes and higher contrast.

Applications

Building an accessible design system, defining a responsive type scale (ratio 1.125 — minor third — is the most common starting point), auditing existing sites for WCAG compliance, designing for elderly audiences or low-vision users. Brazil's LBI (Lei 13.146/2015) explicitly references W3C guidelines for digital accessibility.

FAQ

Is 16px really the minimum? WCAG doesn't mandate an absolute pixel value, but 16px is the browser default and the de-facto industry baseline. Going below 14px on body text harms readability.

Should I use px, rem or em? Prefer rem for body and headings — it respects user zoom and root-size preferences. em is useful for nested components.

What counts as large text? Per WCAG: ≥ 18px regular, or ≥ 14px when bold (≈ 14pt and 18pt in print).