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Agent skill

Fitts Law

by Owl-Listener in Owl-Listener/designer-skills

Apply Fitts's Law — target acquisition time depends on size and distance.

MITAuto-check passedMarketing & SEO

Install Fitts Law

skills CLI
$ npx skills add Owl-Listener/designer-skills --skill fitts-law -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install Owl-Listener/designer-skills fitts-law --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/Owl-Listener/designer-skills.git skills-src && mkdir -p .claude/skills && cp -r skills-src/interaction-design/skills/fitts-law .claude/skills/fitts-law && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
fitts-law
GitHub stars
2.9k
Used in
1 other repo
Token cost
~878 tokens
SKILL.md length
483 words
Files
1
Skills in repo
107
Repo updated
First seen
Licence
MIT

At a glance

Apply Fitts's Law — target acquisition time depends on size and distance.

  • Sizing and positioning controls
  • SKILL.md covers What You Do, The Principle, Practical Implications and Common Design Applications, plus 1 more section
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
  • Especially for touch

What it does

Fitts Law is an agent skill from Owl-Listener/designer-skills. 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.

Its SKILL.md is about 880 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Marketing & SEO. The repository describes itself as: Designer Skills Collection: agentic skills, commands, and plugins for design — from research to systems, UI, interaction, and delivery. The licence is MIT.

When your agent uses it

  • Sizing and positioning controls
  • Especially for touch

Example prompts

  • “/fitts-law”

What it can do on your machine

Read from SKILL.md and the folder at commit 9a6930c. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md.

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Fitts Law loads about 878 tokens when it runs. Until then it costs about 51 tokens; SKILL.md has 483 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~51
When it runs · the whole SKILL.md, loaded when a task matches
~878

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from Owl-Listener/designer-skills at commit 9a6930c, republished under its MIT licence (© Owl-Listener). 483 words, ~878 tokens.

Download SKILL.mdSave it as .claude/skills/fitts-law/SKILL.md (or your agent's skills folder).
name
fitts-law
description
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`.

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)
Target Distance
  • Place related actions near the content they act on — a card action should live on the card, not across the screen
  • Edges and corners of the screen are infinite-size targets (pointer cannot overshoot) — use them for persistent navigation (macOS menu bar, Windows taskbar)
  • On mobile, bottom-of-screen placement reduces reach distance for right-hand thumb use
  • Dialogs with confirmation actions should not require crossing the full screen to reach "OK"
Show full SKILL.md (236 more words)Show less
What Fitts's Law Does Not Cover
  • Cognitive cost: it models motor time, not the time to decide what to tap. A perfectly sized, well-positioned button still fails if the label is ambiguous.
  • Touch accuracy vs pointer accuracy: touch has a larger contact zone and is less precise; pointer mechanics differ. The law applies to both but parameters vary.
  • Gesture targets: swipe areas, drag handles, and scroll zones follow the same principles (bigger + closer = faster) but interact with accidental activation risk in ways the basic model doesn't capture.

Common Design Applications

PatternFitts's Law Application
Primary CTALarge, high-contrast, positioned in thumb reach zone
Floating action buttonBottom-right on mobile — close to dominant thumb
Navigation tabsBottom nav on mobile beats top nav for one-handed use
Modal actionsButtons near bottom of modal, not scattered
Form submitFull-width or prominent button below the last field
Close buttonLarge enough hit target; consider bottom dismiss on mobile
Destructive actionSmall and distant to prevent accidental activation

Best Practices

  • Always test tap target size on real devices — what looks adequate in design tools is often too small in hand
  • Use padding, not visual size, to expand hit targets
  • Do not apply Fitts's Law in isolation to justify oversized buttons; balance with visual hierarchy and spacing
  • On desktop, exploit screen edges for persistent navigation; don't waste them
  • Audit high-error interactions (mis-taps, mis-clicks) first — they are almost always Fitts's Law failures

© Owl-Listener, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in interaction-design/skills/fitts-law of Owl-Listener/designer-skills.

Open the folder on GitHubat commit 9a6930c

Used in 1 other repository

We found 2 copies of this SKILL.md (exact, near-identical or edited) in other folders, from 1 other GitHub owner. This page covers the copy in Owl-Listener/designer-skills, which our catalogue first saw on October 7, 2026.

Compare with similar skills

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Referralscoreyhaines31/marketingskills54k2 repos~2.6kAutomated safety check: PassMIT
SEO GeoReScienceLab/opc-skills1.8k4 repos~2.1kAutomated safety check: PassApache-2.0

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Categories

Questions about Fitts Law

What does Fitts Law do?

Apply Fitts's Law — target acquisition time depends on size and distance. Fitts Law is an agent skill from Owl-Listener/designer-skills. Apply Fitts's Law — target acquisition time depends on size and distance.

When should I use Fitts Law?

Fitts Law fits situations like: sizing and positioning controls; especially for touch.

How do I install Fitts Law in Claude Code?

Run `npx skills add Owl-Listener/designer-skills --skill fitts-law -a claude-code`. Or copy the skill folder (interaction-design/skills/fitts-law in Owl-Listener/designer-skills) into .claude/skills/fitts-law in your project. Claude Code loads it when a task matches its description.

How do I install Fitts Law in Codex?

Run `npx skills add Owl-Listener/designer-skills --skill fitts-law -a codex`. Or copy the skill folder (interaction-design/skills/fitts-law in Owl-Listener/designer-skills) into .agents/skills/fitts-law in your project. Codex loads it when a task matches its description.

Can I use Fitts Law in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add Owl-Listener/designer-skills --skill fitts-law -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/fitts-law, .gemini/skills/fitts-law, .github/skills/fitts-law and .opencode/skills/fitts-law in your project.

What does Fitts Law need to run?

SKILL.md names no scripts, command-line tools or credentials: Fitts Law is instructions for the agent only.

Does Fitts Law access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Fitts Law safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Fitts Law use?

Fitts Law is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Fitts Law use?

About 878 tokens (SKILL.md is roughly 3.5k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Fitts Law?

Skills that share tags, products or a category with Fitts Law: Geo Fundamentals (wasp-lang/wasp, 19k stars), Ab Testing (coreyhaines31/marketingskills, 54k stars), Hreflang and International SEO (AgriciDaniel/claude-seo, 19k stars) and Referrals (coreyhaines31/marketingskills, 54k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Fitts Law?

Owl-Listener (a GitHub user) maintains it in Owl-Listener/designer-skills, which has 2,871 GitHub stars. The repository holds 107 skills in this directory. The repository was last updated on September 5, 2026.

Source: Owl-Listener/designer-skills on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.