thinking-fermi-estimation
Make order-of-magnitude estimates for unknown quantities by decomposing into known or estimable factors. Use for capacity planning, cost estimation, market sizing, and technical feasibility assessment.
Profile →npx skills add majiayu000/claude-skill-registry --skill thinking-fermi-estimation --agent claude-code
Same command for any agent — swap --agent for codex, cursor, copilot.
Weekly change comes from our own snapshots, not the repository page — it measures attention, not adoption.
# Fermi Estimation ## Overview Fermi estimation, named after physicist Enrico Fermi, is the art of making reasonable estimates for quantities that seem impossible to know without direct measurement. By decomposing a question into factors you can estimate, then multiplying, you often get surprisingly accurate order-of-magnitude results. **Core Principle:** Break the unknown into known (or estimable) pieces. Even rough estimates combine to reasonable accuracy due to errors canceling out. ## When to Use - Capacity planning ("How much storage will we need?") - Cost estimation ("What will this infrastructure cost?") - Market sizing ("How many potential users exist?") - Feasibility assessment ("Is this even plausible?") - Sanity checking ("Does this number make sense?") - Interview questions ("How many piano tuners in Chicago?") - Quick prioritization ("Is this worth pursuing?") Decision flow: ``` Need a number you don't have? → yes → Can you measure it directly? → no → FERMI ESTIMATE ↘ yes → Measure ↘ no → You might not need it ``` ## The Fermi Process ### Step 1: Clarify What You're Estimating Be precise about the quantity: ``` Vague: "How big is the market?" Precise: "How many SaaS co
- Overview
- When to Use
- The Fermi Process
- Step 1: Clarify What You're Estimating
- Step 2: Decompose into Estimable Factors
- Step 3: Estimate Each Factor
- Step 4: Combine Factors
- Step 5: Sanity Check
- Step 6: State Confidence and Implications
- Fermi Estimation Template
- Example 1: Data Storage Needs
- Example 2: API Rate Capacity
- Example 3: Market Size
- Common Decomposition Patterns
What does the thinking-fermi-estimation skill do?
Make order-of-magnitude estimates for unknown quantities by decomposing into known or estimable factors. Use for capacity planning, cost estimation, market sizing, and technical feasibility assessment.
How do I install it?
Run `npx skills add majiayu000/claude-skill-registry --skill thinking-fermi-estimation --agent claude-code` — it drops the skill into your project so the agent can pick it up. Swap the --agent value for codex, cursor or copilot if you use one of those.
Where does this skill come from?
From majiayu000/claude-skill-registry, a repository with 534 stars. We read it straight from the repository tree rather than a submitted listing, so what you see here is what is actually published.
Is a popular skill a good skill?
Not necessarily. Stars measure attention, not adoption — a repository can trend for a week and be abandoned. That is why we show the weekly change from our own snapshots next to the total, instead of a single flattering number.