When writing a quote for an order for products, would you write

25K or 25M to refer to 25,000 parts or pounds or units?

  • 25K for 25,000, 25M for 25,000,000.
    – Mitch
    Apr 23, 2013 at 23:34
  • 3
    If you're writing a quote, make it explicit and write 25000.
    – Andrew Leach
    Apr 23, 2013 at 23:35
  • en.wikipedia.org/wiki/Binary_prefix
    – RegDwigнt
    Apr 23, 2013 at 23:50
  • @RegDwighт English numeric abbreviations aren't quite the same as binary prefixes: For example, they generally use uppercase K for thousands and B for billions instead of giga. Apr 23, 2013 at 23:56
  • @Bradd point taken, but that information, too, is to be found on Wikipedia, in fact by following links from that article. Not to mention that in either system the two letters in question mean the same thing, so this is really a non-starter. My comment is only there because when closing a question as general reference, it is considered good practice to provide a link to the "internet reference source designed specifically to find that type of information". In this case that's Wikipedia. Strictly speaking it would be sufficient to link to its home page, or the article on the letter M.
    – RegDwigнt
    Apr 24, 2013 at 1:21

1 Answer 1


In English numeric abbreviations and currency:

  • K for thousand (from kilo)
  • M for million
  • B for billion
  • T for trillion

In metric prefixes for SI measurements:

  • k for thousand (note lowercase)
  • M for million (from mega)
  • G for billion (from giga)
  • T for trillion (from tera)

Therefore, 25K is 25,000 units. You could also write 25k (lowercase k). These abbreviations are appropriate for summary text but not itemized lists or tables. In that case, should not abbreviate (although you may specify all numbers in thousands in the legend if appropriate).

  • 2
    This answer and all discussion on this question miss the point that the asker was specifically mentioning "business quotes." In accounting, M usually means thousands and MM means millions (and K is not used). This is a dumb practice, in my opinion; I would vote to reopen the question as I think it would benefit from a lengthy, canonical answer for when to use M = thousand and how to recognize the authors intent when reading, especially when MM and K are not present.
    – Patrick M
    Aug 25, 2014 at 15:21
  • (The world stopped using Roman Numerals, and not because we ran out of them.)
    – Patrick M
    Aug 25, 2014 at 15:22
  • Thanks for pointing that out! I'd never heard of it. Since it appears to be technical jargon rooted in Latin, it might still be off topic, but it's good to have the information. Maybe I'll edit my answer if I have time. Aug 25, 2014 at 19:07

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