44 Points or Bust

The most important number in mobile design was measured, not designed. An adult index finger pad averages 10–14mm across; a thumb pad, 20–25mm. On a modern phone display, 44 points is roughly 7mm — already a compromise, workable only because the touch system forgives near misses. Go smaller and you're not designing a button, you're designing a lottery.

Apple's Human Interface Guidelines set the floor at 44×44pt in 2010 and have never moved. Material Design says 48×48dp. WCAG 2.2's new minimum is 24×24 CSS pixels — a floor for the web so low it's best read as a legal boundary, not a target.

A miss isn't just a miss. For a user with essential tremor, Parkinson's, arthritis, or simply a phone in one hand and a toddler in the other, an undersized target turns every interaction into a test of motor control the interface was supposed to absorb. The stakes rise with the button: the smallest tap targets in most apps are, notoriously, the close button on the ad and the 'not now' under the paywall.

And the target is not the glyph. A 16-point icon is fine — inside a 44-point touch area. The visible mark and the interactive zone are separate layers, and conflating them is the single most common way small targets ship.

Turn on any layout inspector and measure your five most-tapped controls. The pattern we find in audits, over and over: primary actions pass, because designers care about them, while the controls that fail are the ones users need when something has gone wrong — the retry, the dismiss, the back chevron in the top corner your thumb cannot reach anyway.

44 points is not the ceiling of care. It's the floor. Bust the floor and everything above it is decoration.