Back-of-the-envelope

//ˌbæk‿əv ðiː ˈɛnvələʊp// adj, slang

adj, slang ·Moderate ·College level

Definitions

Adjective
  1. 1
    Especially of a calculation, estimation, or other reasoning, or an idea: approximate, rough, simplified. idiomatic, informal

    "We can do some back-of-the-envelope calculations before all the facts come in."

Synonyms

All synonyms
back-of-the-fag-packetback-of-the-napkin

Example

More examples

"Doing some quick back-of-the-envelope calculations, he reckoned that the raw materials actually cost less than one-thirtieth of the selling price."

Etymology

A reference to a calculation or an idea that occurs to one being jotted down on an available scrap of paper, such as the back of an envelope.

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Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.