When should you use Minimum font size for body text?

Run this on any page where the body copy is the product — documentation, articles, pricing tables, legal pages, checkout copy. It is most valuable as a standing check on pages you do not open often, because a shrunk paragraph is invisible to whoever shipped it and obvious to the person trying to read it. It costs nothing to leave on, so the usual pattern is to include it in every page audit rather than reaching for it after a complaint.

Skip it on pages that are deliberately typographic experiments — a poster-style campaign landing page or a splash screen where oversized display type is the design, not a defect. It is also the wrong instrument for judging whether your type scale is *good*: it answers whether text is readable at all, not whether 15px was the right reading size. If you are auditing a design system's hierarchy, review it against your own tokens instead.

body copy rendered below a readable size; text blown far past its intended size by a broken rule; a stylesheet change that shrank copy sitewide

A failure names the measured size and which end of the range it broke. A size under the floor means text on the live page is effectively unreadable, which is an accessibility defect and usually the result of a cascade problem rather than an intentional choice. A size far over the ceiling almost never means "someone chose 90px body copy" — it means a rule that should have applied to a heading leaked onto the paragraph, or a stylesheet failed to load and the browser is rendering unstyled defaults.

Two parameters carry the check: `minPx` and `maxPx`, defaulting to `6px` and `48px`. The floor is deliberately permissive — it is not a design opinion about your reading size, it is a one-sided test for text that has genuinely stopped being text, so a page setting 14px body copy passes and nobody argues with the tool. The ceiling exists for the same reason in the other direction: it catches the broken-layout and missing-stylesheet cases, where copy renders at heading or unstyled-default scale, without failing legitimate large-type design.

SchemaFirst.org publishes community-governed standards for digital QA. ArbiterQA is a supporter and commercial licensee of those standards; citation does not mean SchemaFirst operates ArbiterQA.