As I understand it, the preferred abbreviation for Number is "No."

If we want to then follow that abbreviation with a colon, like in a form for instance, what does style dictate we do?

Is it:

  • "No.: 0123456789" (i.e. we preserve the period and add a colon) or;

  • "No: 0123456789" (i.e. we remove the period and add a colon) or;

  • "No. 0123456789" (i.e. we preserve the period and do not add a colon)

Is there a strict rule one should follow in this scenario?

Which is preferred stylistically?

Does the convention vary between British and American English?


It's worth mentioning that I'm interested in how this applies to lists of data that use the following format:

First Name: John

Last Name: Doe

ID No.: 0123456789

ID No: 01223465798

ID No. 0123456789


  • I think the abbreviation "No." is not preferred in a context like this. When it is used, it's usually directly before a specific number, like "No. 1." In other contexts, I would write out "Number" in full. Similar to how you can write "p. 22" to mean "page two," but in a form I would write "Page:" instead of "p.:".
    – herisson
    Commented Feb 20, 2016 at 7:17
  • 1
    I tend to agree with sumelic but feel it's important to add that in cases like in your clarification the typical style is ID: 0123456789. Most people can figure out that this is a number on their own. This side steps the style issue completely. If you want to see it dealt with see this similar question: Punctuation around abbreviations Commented Feb 20, 2016 at 8:18
  • @AlfaZulu "Number" can also be represented by "#"
    – Elian
    Commented Feb 20, 2016 at 11:09
  • I don't know how much this rule is followed, but I was told that you only use a period if you are shortening a word before its ending, but not if the abbreviation contains the final letter of the word. So - Mr for Mister, Dr for Doctor, but Rev. for Reverend and Prof. for Professor. If that's the case, 'No' does not have a period as it's short for Latin 'numero'. But you do mostly see it with a period, and I don't think this rule is something to have sleepless nights over :)
    – Mynamite
    Commented Feb 20, 2016 at 12:41

1 Answer 1


Don’t abbreviate. Abbreviations are not standardized and don’t scale to a worldwide audience. Be explicit in order to be understood.

Just write:

First Name: John

Last Name: Doe

ID Number: 0123456789

Same with acronyms. Don’t write “CIA” and assume people will read “Central Intelligence Agency” because CIA also means “Culinary Institute of America” and thousands of other things. So you want to write “Central Intelligence Agency (CIA)” the first time and then “CIA” after that.

  • 3
    Advising 'Don't abbreviate' and retaining 'ID' seem to conflict. Commented Feb 20, 2016 at 10:08
  • Whilst yes I agree good to explain abbreviations upon first usage, possibly ID is so ubiquitous that one can break the rules for it. In same way one would never write "Please do not point a light amplification by stimulated emission of radiation (laser) beam at your colleagues."
    – k1eran
    Commented Feb 20, 2016 at 14:27

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