Design Conditional and Dependent Fields

Forms & Inputs · forms, progressive disclosure, cognitive load

Updated 2026-07-28

Reveal fields based on answers rather than showing every possibility at once. A form that adapts is shorter for everyone and correct for more people.
Add fields below the trigger, never above it. Content appearing above the current position pushes the page and loses the user's place.
Animate the reveal enough to be noticed and not enough to be slow. A field that appears instantly is often missed entirely.
Never disable a field without saying why. A greyed-out input with no explanation is a dead end, so state the condition that would enable it.
Decide what happens to hidden answers, and be consistent:

Update dependent options when the parent changes. A city list that still shows the previous country's cities produces invalid submissions that are hard to explain.
Keep the required rules in step with visibility. A hidden required field blocks submission with an error the user cannot find, which is one of the worst form bugs there is.
Show the whole shape of the form somewhere. If the length changes as people answer, a step count or a summary keeps it from feeling endless.

Conditional logic is a conversation, and it goes wrong when the interface forgets what it already asked.