back-of-the-envelope

alternative back-of-an-envelope

1. idiomaticinformalEspecially of a calculation, estimation, or other reasoning, or an idea: approximate, rough, simplified.First known use 20th c.

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

   5 more examples

   [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.

   1964 February 20, Edgar M[aurice] Cortright, witness, “Statement of Edgar M. Cortright, Deputy Associate Administrator for Space Science and Applications, NASA; Accompanied by Dr. John F. Clark, Director of Sciences, Office of Space Sciences and Applications”, in 1965 NASA Authorization: Hearings before the Subcommittee on Space Sciences and Applications of the Committee on Science and Astronautics, U.S. House of Representatives, Eighty-eighth Congress, Second Session on H.R. 9641 (Superseded by H.R. 10456) […] No. 1, Part 3 […], Washington, D.C.: U.S. Government Printing Office, →OCLC, page 1548

   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.

   1966 March 17, Arthur M[elvin] Okun, witness, “Council of Economic Advisers: Salaries and Expenses”, in Departments of Treasury and Post Office and Executive Office Appropriations for 1967: Hearings before a Subcommittee of the Committee on Appropriations, House of Representatives, Eighty-ninth Congress, Second Session […], Washington, D.C.: U.S. Government Printing Office, →OCLC, page 713

   On one defense item, somebody kept referring to it as a back-of-an-envelope cost estimate. Do you have a back-of-an-envelope cost estimate?

   1979 February 22, Thomas F[rancis] Eagleton, “Department of Labor: Labor-management Services Administration: Statement of Jack A. Warshaw, Deputy Assistant Secretary for Labor-management Relations …”, in Departments of Labor and Health, Education and Welfare and Related Agencies Appropriations for Fiscal Year 1980: Hearings before a Subcommittee of the Committee on Appropriations, United States Senate, Ninety-sixth Congress, First Session: Part 1 […], Washington, D.C.: U.S. Government Printing Office, →OCLC, page 464

   Apart from those manuscripts which were intended as more or less complete, self-contained works, [William] Petty left a huge body of papers, much of which amounts to fragments and hastily written private notes – many the seventeenth-century equipvament of back-of-the-envelope calculations and comments. These papers constitute a further testament to his sustained investigation of economic and political subjects.

   1996, Tony Aspromourgos, On the Origins of Classical Economics: Distribution and Value from William Petty to Adam Smith (Routledge Studies in the History of Economics), Abingdon, Oxfordshire; New York, N.Y.: Routledge, published 2000, →ISBN, →ISSN

   The reader will not need to be warned that the calculations involved are of the back of an envelope type and statements of the form ‘a equals b’ should be read ‘a equals b approximately’ or even ‘with a bit of luck, a and b will be of the same order of magnitude’.

   1996, T[homas] W[illiam] Körner, “Biology in a Darkened Room”, in The Pleasures of Counting, Cambridge, Cambridgeshire: Cambridge University Press, published 2002, →ISBN, part II (Meditations on Measurement), pages 112–113

   Synonyms: back-of-the-fag-packet, back-of-the-napkin