The 24-pixel rule
most sites fail

Nine new criteria, one you can measure

WCAG 2.2 added nine success criteria. Most of them concern things a machine cannot judge: whether an authentication step demands a cognitive test, whether help is in a consistent place, whether a task can be completed without dragging. One of them is a measurement, which means a tool can check it, which means you will be held to it. It is 2.5.8, Target Size (Minimum), at level AA.

What it asks

Anything you interact with — a link styled as a button, a checkbox, a tab, a close icon — must be at least 24 by 24 CSS pixels, or be spaced far enough from its neighbours that a 24-pixel circle around it would not touch another target. There are exemptions, and the useful one is inline links inside a paragraph: a link in a sentence is not expected to be 24 pixels tall.

Why so many sites fail it

Icon-only buttons are the usual culprit. A 16-pixel close icon with 2 pixels of padding is 20 by 20, looks fine on a designer's monitor, and is genuinely hard to hit for anyone with a tremor, or on a bus. Dense toolbars, tag chips, star ratings and pagination links are the other common offenders. All of them pass a visual review and fail a measurement.

Twenty-four is the floor, not the target

24 pixels is the minimum for conformance. Both major platform guidelines have asked for more for years — around 44 pixels on iOS and 48 on Android — because those numbers come from research on actual fingers. Treat 24 as the line below which you are non-conformant, and 44 as the size you should be aiming at for anything touched on a phone.

Checking your own pages

The accessibility checker on this site measures every interactive element after rendering and reports anything under 24 by 24, marked as new in 2.2 so you can see which failures come from the update. It also covers contrast, labels, headings and link names — the checks where automation is trustworthy. It will not tell you whether your alt text is any good; nothing can.