Originally a colloquial axiom in US economics, though now in general use. The proverb implies that you cannot get something for nothing.

‘Oh, “tanstaafl.” Means “There ain't no such thing as a free lunch.” And isn't,’ I added, pointing to a free lunch sign across the room, ‘or these drinks would cost half as much.’
[1967 R. A. Heinlein Moon is Harsh Mistress xi.]

I was taught‥the first and only law of economics: ‘There is no such thing as a free lunch.’
[1969 Newsweek 29 Dec. 52]

There is no such thing as a free lunch. ‥The idea has proved so illuminating for environmental problems that I am borrowing it from its original source, economics.
[1971 New Yorker 25 Sept. 76]

There's no such thing as a free lunch. So, in return for your help, what do you ask?
[1979 L. St. clair Obsessions xi.]

I believe that the old saying ‘There is no such thing as a free lunch’ applies here. Pornography and permissiveness will have a price.
[2001 Spectator 29 Dec. 26]

Related to: bribery and corruption; reciprocity

Bibliography of major proverb collections and works cited from modern editions is available here.

The Oxford Dictionary of Proverbs. Copyright © 1982, 1992, 1998, 2003, 2004 by Oxford University Press. All rights reserved.