Text Readability Checker
How vexingly quick daft zebras jump over the lazy dog. Reading comfort depends on size, line height, and the distance between your eyes and the glass. Judge this paragraph the way you actually sit.
縁側で緑茶を飲みながら朝の新聞を読む。漢字は画数が多いほど小さなサイズで潰れやすいので、日本語の本文は少し大きめが安心です。
Sizes here are CSS pixels; your OS scaling and browser zoom sit on top of them, which is exactly why checking on your own screen matters.
How it works
仕組みHow small is too small? Drag the slider and read real paragraphs, in English and Japanese, at any size from 12 to 32 pixels, with live conversions to points and rem on the meters. A fixed comparison stack shows the same sentence at 12, 14, 16, 18, and 24 pixels so you can judge the steps side by side. This is a test only your own screen can run: the same “16px” covers wildly different physical sizes across a phone, a laptop, and a 4K monitor with scaling, so the honest answer comes from reading it on the device in your hands, at the distance you actually sit.
No, WCAG doesn’t mandate a minimum font size. What it does require is that text can be resized up to 200% without loss of content. That said, 16px body text is the near-universal accessibility recommendation because browser defaults, rem units, and reader comfort all centre on it.
A CSS pixel is the web’s base unit; a point is a print unit fixed at 3∕4 of a CSS pixel, so 16px equals 12pt. Rem is relative to the root font size: 1rem is 16px unless the user changed their browser default, which is exactly why accessibility guides prefer rem: it respects that choice.
Kanji pack many strokes into the same square a Latin letter uses, so fine detail collapses sooner as sizes shrink: 縁 or 飲 turn to grey smudges below roughly 14px on a standard-density screen. Japanese body text is typically set a size or two larger, with more generous line height.