back-of-the-envelope

Definition

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

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.

Example Sentences

• "We can do some back-of-the-envelope calculations before all the facts come in."
• "[T]he original estimates are frequently back-of-the-envelope-type estimates made internally without detailed engineering studies, if you go all the way back to Day 1."
• "We joke about having to make back-of-the-envelope calculations, while in the university environment we might spend 2 or 3 weeks computerizing the calculations. I might say, however, that making back-of-the-envelope calculations and later checking them out on computers has impressed me that we have developed a considerable skill in back-of-the-envelope calculations."