Fermi estimate
Say it: FUR-mee ES-tih-mut /ˈfəːmi ˌɛstɪmət/ · noun
What “Fermi estimate” means
A rough calculation built from sensible guesses.
More precisely: A rough calculation of a hard-to-know quantity using reasonable assumptions and simple arithmetic.
When to use it
In practical problem-solving, when an exact answer is unavailable but sensible assumptions can give a useful rough figure.
Similar words
back-of-the-envelope calculation, rough estimate, ballpark figure
Where it comes from
Named after physicist Enrico Fermi, famous for quick, surprisingly accurate rough estimates.
Quick check
You estimate daily café sales from tables, customers per table and average spending, without seeing the accounts. What are you making?
a Fermi estimate or an exact calculation?
Show the answer
a Fermi estimate
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