Matching swipe distance to the number of actions

What it is

How many actions a row reveals, each needs a horizontal slice. A short swipe crushes them into untappable color chips; a long swipe is dragging the whole row away, closer to a full-swipe commit and to horizontal scroll. Distance has to match count: two or three actions each get a tappable minimum width, and total travel still stays well under half the screen.

Why it happens

Every revealed button is a touch target whose width is bounded by finger size. Four actions side by side on a phone almost require sliding the whole row to see them all; the interval between “reveal the menu” and “full-swipe commits the default” is then crushed, and the classifier can barely stop in the middle. More actions also make people read labels mid-swipe, so motion and reading fight for the same time. A healthy shape is one or two primary actions per side, with the rest behind “more” that opens a menu—one extra tap in exchange for a short, stoppable travel.

Studying it

Build the same row with 1, 2, 3, and 4 revealed buttons. Measure success at stopping in a tappable region, accidental full-swipe commits, and wrong-button taps. Independent variables include button width and whether labels are shown. Eye tracking shows whether labels sit under the finger. Split screen widths; four buttons hurt less on a tablet.

Where it stops holding

Desktop or landscape width can hold more side by side, but blowing up a four-button phone layout is not a fix—target height is unchanged. Icon-only buttons can be slightly narrower, at a recognition cost. RTL mirrors swipe direction; distance matching still holds, left and right swapped.

Applying it

• At most two direct buttons per side; from the third on, use “more.” Each direct button wide enough for a one-finger tap.
• Keep reveal travel clearly shorter than full-swipe commit, with a stable rest in between. Do not let four chips run to the screen edge.
• Have people reveal and tap the second button. If they always overshoot into committing the first, or the second is too thin to hit, count and distance are unmatched.

Related

• Same group: C3.17.1 Actions revealed by swiping a row are hidden functions · C3.17.3 The danger of a full swipe that executes immediately · C3.17.4 Destructive actions should not be the default full-swipe action
• Adjacent: C2.02 Minimum touch target size · C3.05 Swipe
• Search: swipe action width · trailing actions · touch target