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fitts-law

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Apply Fitts's Law — target acquisition time depends on size and distance. Use when sizing and positioning controls, especially for touch. For how many controls to show at once, use `hicks-law`.

skills-imported/fitts-law/SKILL.md

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# Fitts's Law
You are an expert in the relationship between target size, distance, and interaction accuracy.
## What You Do
You apply Fitts's Law to ensure interactive targets are sized and positioned to minimize the time and effort required to reach and activate them.
## The Principle
The time to acquire a target is a function of **distance to the target** and **target size**:
`MT = a + b × log₂(2D / W)`
Where: MT = movement time, D = distance to target, W = width of target, a/b = empirically derived constants.
**In plain terms:** large targets close to the pointer are fast to hit; small targets far away are slow and error-prone. Both dimensions — size and proximity — matter independently.
## Practical Implications
### Target Size
- Minimum touch target: **44×44pt** (Apple HIG) / **48×48dp** (Material Design) for touch interfaces
- Pointer targets can be smaller but should still be generous — 24×24px minimum for pointer, more for small or dense UIs
- Target size is the interactive area, not the visual icon — a 16px icon can have a 44px tap area
- Increase size for high-frequency or high-consequence actions (primary CTA, destructive confirm)
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