Target size, and the two criteria that disagree
WCAG 2.2 added a 24×24 minimum at AA. The 44×44 figure everyone quotes is AAA and Apple's guideline.
Target size, and the two criteria that disagree
WCAG 2.2 added a 24×24 minimum at level AA. The 44×44 figure everyone quotes is level AAA and Apple's guideline — both real, both different, and worth telling apart.
What each figure is
2.5.8 Target Size (Minimum), AA, WCAG 2.2: 24×24 CSS pixels, with exceptions. A smaller target passes if there is enough spacing around it — specifically if a 24-pixel circle centred on it does not overlap the circle of any adjacent target.
2.5.5 Target Size (Enhanced), AAA: 44×44 CSS pixels. This is the number usually quoted as "the WCAG requirement", and it is the enhanced level rather than the one most projects are held to.
Apple's Human Interface Guidelines say 44×44 points. Android's Material guidance says 48×48 dp. Neither is WCAG; both are worth meeting.
The inline exception covers a link inside a sentence, where the target is determined by the line height and enlarging it would break the text. That exception does not extend to a button that happens to sit in a paragraph.
Spacing counts toward the minimum
A row of 20-pixel icons packed together fails. The same icons with 12 pixels between them can pass, because the criterion is about whether you can hit one without hitting its neighbour.
That makes padding as useful as size, and it is often easier to add — a 24-pixel icon in a 44-pixel padded button keeps the visual weight and gains the target.
The tap target is not the visible box
Padding, and a pseudo-element stretched over the parent, both enlarge the hit area without changing what is drawn. The CSS below does the second, which is how most icon buttons get to 44 without looking like it.