estimation-fermi

SKILL.md

Fermi estimation provides rapid order-of-magnitude answers to seemingly impossible questions by decomposing them into smaller, estimable parts. This skill guides you through decomposition strategies, bounding techniques, sanity checks, and triangulation to make defensible estimates when data is scarce, time is limited, or precision is unnecessary for the decision at hand.

Trigger phrases: "ballpark estimate", "order of magnitude", "back-of-envelope", "roughly how many", "feasibility check", "gut check", "triangulate", "sanity check"

Fermi estimation (named after physicist Enrico Fermi) breaks down complex unknowns into simpler components that can be estimated using common knowledge, constraints, and reasoning. The goal is not precision but being "right to within a factor of 10" quickly.

Use when making quick order-of-magnitude estimates under uncertainty (market sizing, resource planning, feasibility checks), decomposing complex quantities into estimable parts, bounding unknowns with upper/lower limits, sanity-checking strategic assumptions, or when user mentions Fermi estimation, back-of-envelope calculation, order of magnitude, ballpark estimate, triangulation, or needs to assess feasibility before detailed analysis. Source: lyndonkl/claude.

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