fermi-estimation
Fermi Estimation
Core principle: Almost any quantity can be estimated to within an order of magnitude by decomposing it into components you can estimate, then multiplying through. The goal is not precision — it's getting the right number of zeros. A 10× error is informative. A 1000× error changes the decision.
"It is better to be approximately right than precisely wrong." — Carveth Read
Why Fermi Estimation
You're not always in a position to measure. But you often need to decide. Fermi estimation gives you:
- A defensible, traceable quantitative estimate from reasoning alone
- A sanity check on received numbers ("does this feel right order-of-magnitude?")
- Identification of the key driver — the variable that dominates the result
- A structured way to surface which sub-estimates need validation most
The Core Process
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