Language: en
Meaning: (idiomatic,informal)Especially of acalculation,estimation, or otherreasoning, or anidea:approximate,rough,simplified.[from 20th c.]Synonyms:(UK)back-of-the-fag-packet,(US)back-of-the-napkinWe can do someback-of-the-envelopecalculations before all the facts come in.1964February 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”, in1965 NASA Authorization: Hearings before the Subcommittee on Space Sciences and Applications of theCommittee on Science and Astronautics,U.S. House of Representatives, Eighty-eighthCongress, Second Session on H.R. 9641 (Superseded by H.R. 10456)[…]No. 1, Part 3[…], Washington, D.C.:U.S. Government Printing Office,→OCLC,page1548:[T]he original estimates are frequentlyback-of-the-envelope-type estimates made internally without detailed engineering studies, if you go all the way back to Day 1.1966March 17,Arthur M[elvin] Okun, witness, “Council of Economic Advisers: Salaries and Expenses”, inDepartments of Treasury and Post Office and Executive Office Appropriations for 1967: Hearings before a Subcommittee of theCommittee on Appropriations,House of Representatives, Eighty-ninthCongress, Second Session[…], Washington, D.C.:U.S. Government Printing Office,→OCLC,page713:We joke about having to makeback-of-the-envelopecalculations, while in the university environment we might spend 2 or 3 weeks computerizing the calculations. I might say, however, that makingback-of-the-envelopecalculations and later checking them out on computers has impressed me that we have developed a considerable skill inback-of-the-envelopecalculations.1979February 22,Thomas F[rancis] Eagleton, “Department of Labor: Labor-management Services Administration: Statement of Jack A. Warshaw, Deputy Assistant Secretary for Labor-management Relations[...]”, inDepartments of Labor and Health, Education and Welfare and Related Agencies Appropriations for Fiscal Year 1980: Hearings before a Subcommittee of theCommittee on Appropriations,United States Senate, Ninety-sixthCongress, First Session: Part 1[…], Washington, D.C.:U.S. Government Printing Office,→OCLC,page464:On one defense item, somebody kept referring to it as aback-of-an-envelopecost estimate. Do you have aback-of-an-envelopecost estimate?1996,Tony Aspromourgos,On the Origins of Classical Economics: Distribution and Value from William Petty toAdam Smith(Routledge Studies in the History of Economics)[1], Abingdon, Oxfordshire; New York, N.Y.:Routledge, published2000,→ISBN,→ISSN:Apart from those manuscripts which were intended as more or less complete, self-contained works,[William] Pettyleft a huge body of papers, much of which amounts to fragments and hastily written private notes – many the seventeenth-century equipvament ofback-of-the-envelopecalculations and comments. These papers constitute a further testament to his sustained investigation of economic and political subjects.1996,T[homas] W[illiam] Körner, “Biology in a Darkened Room”, inThe Pleasures of Counting, Cambridge, Cambridgeshire:Cambridge University Press, published2002,→ISBN, part II (Meditations on Measurement),pages112–113:The reader will not need to be warned that the calculations involved are of theback of an envelopetype and statements of the form ‘aequalsb’ should be read ‘aequalsbapproximately’ or even ‘with a bit of luck,aandbwill be of the same order of magnitude’.1998,Paul Lawrence Rose, “The Bomb as Reactor: The U235 Bomb Misconceived, 1940”, inHeisenberg and the Nazi Atomic Bomb Project: A Study in German Culture, Berkeley; Los Angeles, Calif.; London:University of California Press,→ISBN,page115:Misapplying a basic feature of diffusion theory,[Werner] Heisenbergarrived at an impossibly high figure for a critical mass of pure U235. This was done by means of a seductively simple "back of an envelope" calculation in 1940,[…]1999winter,David A[lexander] Wolf, “Wow! The Earth! Just a Little E-mail from a Guy in Outer Space”, inPeter Warshall, editor,Whole Earth: Access to Tools, Ideas, and Practices, San Rafael, Calif.:Point Foundation,→ISSN,→OCLC,page89, column 1:Back of the envelopecalculation: I've traveled roughly 17 million miles since we left the crew quarters at Cape Kennedy, not including the van ride to the pad … in fact, Earth seems a bit dreamlike these days, as we are connected only by crackling voices on the radio and the photographs brought along and our memories.2010, David G. Thomson, quotingPradeep Sindhu,Mastering the 7 Essentials of High-Growth Companies: Effective Lessons to Grow Your Business[2], Hoboken, N.J.:John Wiley & Sons,→ISBN:I remember very distinctly in October 1995, after I completed my paper design, I had an epiphany. Thisback-of-the-envelopedesign was five years ahead of its time.2010March,Kirk McKusick, Sean Quinlan, quoting Sean Quinlan, “GFS[Google File System]: Evolution on Fast-forward”, inMoshe Y[a’akov] Vardi, editor,Communications of the ACM, volume53, number 5, New York, N.Y.:ACM Media,→DOI,→ISSN,→OCLC,page45, column 3:[I]t quickly became apparent that the natural mapping we had thought of—and which seemed to make perfect sense back when we were doing ourback-of-the-envelopeestimates—turned out not to be acceptable at all.[2021March 24,Christian Wolmar, “Railways Must Sell Themselves and Offer a Better Product”, inRail, number927, Peterborough, Cambridgeshire:Bauer Media,→ISSN,→OCLC, page46:Now, those Treasury mandarins unfamiliar with the railway might assume on theback of an envelopethat if only 80% of trains are running, then that will cost 20% less. If only it were that simple.]
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