A FAB should carry only one primary action

What it is

A FAB is priced, in space and attention, as “the one thing this screen most wants done”: compose, capture, start a chat. It should carry a single primary action. Expanding the plus into a speed-dial cluster, or letting the same FAB become a different verb on every page, turns a primary trigger into a menu that happens to sit in a fixed corner. Menus may exist; they should not wear a FAB’s shell. The shell promises immediate execution, not a second choice.

Why it happens

The circle, the contrast, and the thumb-zone placement say “press this and that thing happens.” A cluster splits one press into “press plus, then choose among equally tiny icons,” stuffing a Hick choice back into the control that was supposed to end choice. People also have to remember what the cluster holds; a wrong memory hits the wrong child action, often unlabeled. Reusing the slot across pages while swapping the icon looks like saving a control; it actually trains “the lower right can do anything,” hollowing out predictability. A FAB’s value is a stable mapping: this place = that create action in this product. Once the mapping becomes a menu or a chameleon, it is no longer worth occluding content relative to an ordinary primary.

Studying it

Compare three ways to complete “create”: a single-action FAB, a speed-dial cluster, an ordinary bottom-bar button. Measure time from intent to done, wrong child actions, and whether people can later say what the lower-right control will do.

Independent variables: number of children, whether children have words, whether the FAB icon changes per page. Dependent variables: decision time, wrong child actions, cross-page expectation agreement.

Speed dial looks powerful in a demo because the presenter already knows the cluster. First-use with novices is what reveals its cost against a single-action FAB.

Where it stops holding

A few products have a “create” that is always a type choice (note / checklist / recording). Speed dial then fronts that choice. Even so, children need words and should be few. An extended FAB still carries one verb, not two. A desktop central “new” can open a full picker because it never made the circular promise of immediate execution.

Applying it

• Give the FAB one product-stable verb (compose, capture). Do not retarget it to search, share, or delete per page.
• When several create types exist, prefer a labeled chooser rather than a ring of unlabeled mini-circles.
• If a speed dial is unavoidable, cap children at three, label each, and do not treat opening the cluster as completing the action.
• Verify by asking on three different pages what pressing the lower right will do. Three different answers, or “it will pop more things,” means the FAB is no longer a single primary.

Related

• Within the group: E1.05.1 A floating action button occludes content underneath · E1.05.3 Show/hide rules while scrolling must stay consistent
• Adjacent: E1.01 Button hierarchy · E1.14 Button groups and split buttons · E1.04 Icon-button ambiguity
• Search terms: floating action button · speed dial · single primary action