99% of the time, I'm clear on when I should use "a" versus "an." There's one case, though, where people & references I respect disagree.

Which of the following would you precede with "a" or "an," and why?

  • FAQ

[Note: I've read the questions "A historic..." or "An historic…"? and Use of "a" versus "an", but the rules given there don't necessarily apply here.]

[Edited to add]

Here's a shorter (and hopefully clearer) version of the question… In written English, which is correct (and why): "a FAQ" or "an FAQ"?

Some references with differing opinions:

  • 12
    "An RPG". The controlling factor is whether it's spoken with a vowel sound. (So "an hour", "a unicorn", etc.)
    – chaos
    Commented Feb 6, 2011 at 4:46
  • 29
    This does raise questions about when there are multiple common pronunciations of the acronym. Like "SQL" is sometimes pronounced "es-kew-el", and sometimes "sequel". The former would call for "an" and the latter for "a". I think, though, that we always choose "a" or "an" based on pronunciation of the acronym and not the spelled-out words, e.g. "an SST", as in "an ess-ess-tee", not "a supersonic transport".
    – Jay
    Commented Sep 30, 2011 at 14:32
  • 8
    @Jay SQL: In which case the writer picks their own style (or follows the in-house style) and uses it consistently.
    – Hugo
    Commented Sep 30, 2011 at 15:10
  • 8
    Or rephrases all sentences with SQL to avoid putting either "a" or "an" in front of it.
    – yoozer8
    Commented Sep 30, 2011 at 17:25
  • 6
    @Jim: While I admit to sometimes rephrasing a sentence to avoid a spelling or grammar problem, that is the coward's way out!
    – Jay
    Commented Oct 4, 2011 at 15:09

10 Answers 10


It depends on whether the abbreviation is an acronym or an initialism.

  • As "fubar" and "scuba" are usually pronounced as a word (making them acronyms), it would make sense to say "a fubar" and "a scuba diver".
  • "FAQ" is a bit harder, because I have heard people say it like an initialism: "‹f›‹a›‹q›", while others pronounce it as an acronym /fæk/.
    Therefore, one should write either "a FAQ" (/fæk/) or "an FAQ" (‹f›‹a›‹q›) depending on how that person pronounces it, ie, whether it is an acronym or an initialism.
  • 22
    Thanks for the teaching :-) Indeed there is a difference in the strict sense :-) So is CD-ROM an acronym or an initialism? Commented Aug 16, 2010 at 9:08
  • 4
    @Dori - yes. Whichever way you write it, it will trip up some readers. The Corpus of Contemporary American English (COCA) lists two results for "a FAQ", and one result for "an FAQ", so "a FAQ" is probably more common. Google also shows a preference for "a FAQ". Commented Aug 17, 2010 at 0:12
  • 5
    The whole “ acronyms must be pronounced as words” distinction appears to be one that is only made by dictionaries. From what I can tell, any abbreviation that is made from initials is called an acronym if it is pronounced differently from what the initials stand for.
    – nohat
    Commented Aug 18, 2010 at 14:56
  • 4
    It appears that the answer is: "there is no definitive answer to this question." Not exactly what I'd hoped, but as this was the only answer that responded to the question I asked, I guess that makes it the best.
    – Dori
    Commented Aug 20, 2010 at 4:04
  • 4
    @mgb Amazingly. If I just "a SQL database" I will automatically pronounce it sequel in my head without even thinking about it. Using "an" I will automatically spell it out in my head.
    – Cruncher
    Commented Jul 14, 2014 at 19:36

The important point to remember is the following:

Written language is a representation of the spoken word.

Thus, the answer is "If the word following the indefinite article begins with a vowel sound, use an; if it begins with a consonant sound, use a."

In the case of initialisms and acronymns, use the exact rule above. For initialisms (e.g. "US"), the individual letters are pronounced. With what sound does the first pronounced letter begin? In the example "US", the first sound is /j/ (or "y"). This is a consonant sound, despite the letter "U" being a vowel; thus, you use a, as in a US dollar.

Contrast this with the initialism "RPM", which begins with the consonant "R" but is pronounced starting with /a/; thus, you use an, as in an RPM counter.

  • 1
    'Written language is a representation of the spoken word.' Yes, but certain conventions are used that are not etically transparent. Does one read out the period's in U.S. (probably still more commonly encountered than US)? How would an expert in spoken English who has never seen written English know not to read them out? The rule Use 'an' if and only if the following sound is ... is certainly almost universal (there remains at least one grey area), but you really need to add supporting evidence. Some arrogater (String & Write, say) may have forced a less sensible 'rule' on us in the past. Commented Oct 29, 2019 at 11:34
  • @EdwinAshworth I doubt one can be an expert in spoken English without having seen written English.
    – Lambie
    Commented Dec 12, 2022 at 16:42

The rule about the usage of a and an as indefinite articles is that an is used before a vowel sound.

  • A warranty (/ˈwɑːrənti/)
  • A user (/ˈjuːzər/)
  • A one-way (/ˈwən ˌweɪ/)
  • A man (/mæn/)
  • An angel (/ˈeɪnʤəl/)
  • An information (/ˌɪnfərˈmeɪʃən/)

When used before an acronym, the rule is still valid, but which article to use depends from how the acronym is pronounced (letter by letter, or as a word).

  • An MP3 (/ɛm pi θri/)
  • An RPG (/ɑːr pi ʤi/)
  • An FBI agent (/ɛf biː aɪ/)
  • A GPS device (/ʤi pi ɛs/)
  • A NASA employee (/ˈnæsə/)
  • @chaos: It doesn't seem that I am the only one to refer to the NOAD; your comments about me (and not to my question) make me think you are saying that I am the only one reporting what the NOAD says, which is not true at all. It also seems that your comments are against me, not against using the NOAD as a reference. I don't think the NOAD is a substandard English guide, and there are many people who would not say the NOAD is a substandard English guide.
    – avpaderno
    Commented Feb 6, 2011 at 8:57
  • 3
    @chaos: The distinction between acronym and initialism is a neologism that is not maintained by all writers or dictionaries. In fact, the Wikipedia page you linked cites The Cambridge Encyclopedia of the English Language: "However, some linguists do not recognize a sharp distinction between acronyms and initialisms, but use the former term for both" and Merriam-Webster's Dictionary of English Usage: "A number of commentators […] believe that acronyms […] pronounceable as words. Dictionaries, however, do not make this distinction because writers in general do not." Etc. Commented Feb 6, 2011 at 11:53
  • 5
    @chaos: As a linguist, I don't consider people's actual usage to be the "lowest common denominator". Why should a self-declared grammar authority's arbitrary decision about the meaning of a word be inherently more "correct" than the way people actually understand the word? Language often isn't precise. There are those who construct artificially precise categories for English lexical items (that don't reflect usage) and then view those who don't conform to those distinctions as being sloppy or poor in their command of English. I see that as a waste of time — we don't learn anything that way.
    – Kosmonaut
    Commented Feb 8, 2011 at 14:33
  • 2
    The "acronym"/"initialism" distinction may not be universally accepted, but it's still probably worth mentioning in an answer that distinguishes between the two types of pronunciation of "acronyms".
    – Mark Reed
    Commented Dec 18, 2016 at 16:37
  • A united .........
    – Zhang
    Commented Apr 3, 2019 at 7:39

Vincent McNabb is correct. If you want evidence based on "credible and/or official sources" that this is the rule followed in formal English writing, here is my suggestion.

I ran Google searches on Google Books only, meaning the bulk of the search will be against professionally edited and published works, not random web sites. I searched only for phrases where the pronunciation of the acronym was relatively clear and consistent: for example, nobody pronounces "SCUBA" as "Ess Cee Yew Bee Ay" and nobody pronounces "FBI" as "Fibbi."

Here are the number of hits in the Google Books database for:

  • "A SCUBA": 49,800
  • "An SCUBA": 56

  • "A FBI": 16,000
  • "An FBI": 343,000

  • "A NASA": 264,000
  • "An NASA": 16,500

  • "A RGB": 7,130
  • "An RGB": 33,800

  • "A UPC": 11,800
  • "An UPC": 436

In each case, basing the article on the initial sound, rather than on the initial letter, is more common; in most cases substantially more common.

As a control, I also looked at two acronyms where both the initial sound and the initial letter are consonants.

  • "A VPN": 50,100
  • "An VPN": 960

  • "A OCR": 9,380
  • "An OCR": 1,870,000

Because "An VPN" and "A OCR" are incorrect based on any possible rule, we can conclude that the positive results are grammatical, OCR, or search engine errors. This suggests that the minority viewpoint on SCUBA, FBI, NASA, RGB and UPC are also smaller than they appear.

We can conclude that, based on evidence of usage among published documents digitized by Google Books, the preferred rule is to base the article on how the intended pronunciation of the acronym would be spelled phonetically.


Note: Some of this information may be extraneous, but take it for what you will!

In general, some acronyms represent nouns, others verbs or adjectives. If it represents the former, I see no problem with prefixing with an (in)definite article (a/an).

scuba is listed as a noun (lower-case) rather than an acronym in most dictionaries these days. It is of course derived from an acronym, but has evolved into a word in its own right (laser would be another example).

FAQ is an acronym, but is very commonly used as a noun - "a list of frequently-asked questions".

FUBAR has various definitions, but it's normally interpreted as an adjective (at least by the original military one).

Hence, I would happily prefix scuba/SCUBA with a/an, but definitely not FUBAR.

All these words begin with hard consonants, and thus should always be prefixed with a. Saying that, some people pronounce FAQ by spelling out its letters, in which case an is appropriate. I've never heard this done with the other two.

  • 2
    When used in the military sense, "fubar" would not have a(n) before it. However, when used in other senses where it is a noun, it would be perfectly fine. It would also be fine to say, "Man, this is a fubar situation". As the article refers to the noun, "situation", which is being modified by the adjective, "fubar". Commented Aug 16, 2010 at 9:26
  • @Vincent: Yeah, but that's slightly beside the point. I mentioned that fubar is used as an adjective, this 'a' is just applying to the 'situation'.
    – Noldorin
    Commented Aug 16, 2010 at 10:13
  • @Noldorin I agreed with your point and added extra information. You are welcome to edit your post and clarify. Commented Aug 16, 2010 at 10:45
  • 5
    The question is which to use between "a" and "an", not whether to use them. The part of speech has nothing whatever to do with this question: it's all on the pronunciation.
    – Colin Fine
    Commented Aug 16, 2010 at 13:20
  • @Colin: The question was not clear to me. It seemed to be asking too different things. Just because I provided more info that may have been necessary, think twice whether that really deserves a down-vote.
    – Noldorin
    Commented Aug 16, 2010 at 13:33

It doesn't make any difference at all whether the article is modifying an acronym, an initialism, a proper noun, a French borrowing, or anything else. English article form is determined solely and entirely by pronunciation. And not at all by spelling.

The rule for the pronunciation of articles in English -- definite and indefinite -- is that they have one form before consonants (note, real consonants -- sounds -- not "letters" in a writing system), and a different form before vowels (note, ditto).

Hence, how you say it is what counts. Nothing else does.

  • Before vowels -- Indefinite an /ən/ and Definite the /ði/:
    an hour, an SOS, an A-to-Z selection, an EE degree, an idiot
    the hour, the SOS, the A-to-Z selection, the EE degree, the idiot (all pronounced /ði/)

  • Before consonants -- Indefinite a /ə/ and Definite the /ðə/:
    a URL, a snafu, a Charlie Foxtrot, a moron
    the URL, the snafu, the Charlie Foxtrot, the moron (all pronounced /ðə/)

Most native English speakers never notice that there are two different pronunciations for the, but non-native English speakers need to know this immediately.


Like @Vincent McNabb said, it is a question of whether the word is used as an initialism (like HTML) or a acronym. When in doubt, as with FAQ, I would defer to the initialism form ("an FAQ") as it suggests in Wikipedia:

There is also some disagreement as to what to call abbreviations that some speakers pronounce as letters and others pronounce as a word. For example, the terms URL and IRA can be pronounced as individual letters: /ˌjuːˌɑrˈɛl/ and /ˌaɪˌɑrˈeɪ/, respectively; or as a single word: /ˈɜrl/ and /ˈaɪərə/, respectively. Such constructions, however—regardless of how they are pronounced—if formed from initials, may be identified as initialisms without controversy.

  • The initialism (non-acronym) is pronounced 'an FAQ'. Commented Aug 17, 2020 at 13:15
  • @EdwinAshworth FYI I interpreted Lynn's "a FAQ" as an acronym b/c it can be read as a single word (faq), which is how I normally hear it in videos but some people do read each letter separately. In any case, the answer provides a link and supporting evidence which is more than the majority of answers posted here.
    – Mari-Lou A
    Commented Dec 12, 2022 at 12:29
  • @Mari-Lou A I was addressing << I would defer to the initialism form ("a FAQ") >> Commented Dec 12, 2022 at 19:37
  • @EdwinAshworth Maybe Lynn will clarify one day Wikipedia: regardless of how they [initialisms] are pronounced, which, I think, means “a FAQ” is still acceptable.
    – Mari-Lou A
    Commented Dec 12, 2022 at 19:50
  • @Mari-Lou A << I would defer to the initialism form >> forces << ("an FAQ") >>. It is a restatement, not an identifier (restrictive) usage, which would be << I would defer to the initialism form "an FAQ" [as opposed to ...] >> Commented Dec 12, 2022 at 19:57

Edit: I originally posted this answer to the question Is there an exceptional use of the article ‘a/an’? which has been merged with this one. The acronyms FTA and FC I refer to below are from that question.

Original answer: It is exactly as you said: an is used before words beginning with a vowel sound, not necessarily a vowel letter.

The acronyms you mentioned both begin with vowel sounds (/ɛf.tiˈeɪ̯/, /ɛfˈsiː/), so an is used before them. There are also words and acronyms that begin with a vowel letter, but not with a vowel sound: a UAV (/ju.eɪ̯ˈviː/), a union (/ˈjuːnjən/).

It depends on the pronunciation of the following word (not its spelling) whether you use a or an.

  • Thank you so much! Your detailed explanation and examples also helped me solve my curiosity :) Have a good day Commented Nov 12, 2018 at 10:28

Compare with an umbrella uttered as /əmˈbrelə/, versus a university uttered as /juːnɪˈvɜːsɪtɪ/. Though both begin with the same written vowel, they have a different sound at the beginning. Umbrella has a schwa, while university has a 'you'. It is the sounds rather that the written vowel that drive the choice of 'a' or 'an'.

It is similar with your question. "An Eff Tee Ay" or "an Eff See". It is the spoken'Eff', uttered with a vowel sound as /ef/, that drives the use of 'an' even though [f] is listed as a consonant.

  • You might have to add the link to the duplicate question. The post has since been merged with the much older question.
    – Mari-Lou A
    Commented Nov 12, 2018 at 16:18

The problem with a vs an with acronyms and abbreviations is that you can't always be sure how the reader will read it. For example, some people might read SIN and say s-i-n while others might say sin, and yet others might say social insurance number. This means it's impossible to have a blanket rule, and therefore it only makes sense to do it however makes sense for yourself (and be consistent), or if possible, whatever makes sense for your audience.

  • (Surprisingly, nobody else mentioned that acronyms and abbreviations can be read with their constituent parts, nor suggested catering to the reader, so I figured I'd post a full answer instead of a comment. 🤷)
    – Synetech
    Commented Jun 8, 2020 at 20:35
  • But the best answer is 'do what 95+% of proficient Anglophones do'. Pythons might pronounce SIN 'luxury yacht' say, but should not be accommodated. Commented Aug 16, 2020 at 16:23
  • What? Are you saying that you never say s-i-n? And where did you get your stats? How can you prove that 95% of people say sin? And even if that were the case, so what? Are you saying that 5% of people should just be ignored and go to hell? 🤨
    – Synetech
    Commented Aug 16, 2020 at 23:15
  • ELU looks at standard usage by proficient Anglophones. It is not targetted at catering for all possible misinterpretations / non-standard practices. Answers should reflect this view, found at the Help Center here. // If both acronym and initialism are commonly used and there remains a debate about which form of the indefinite article should (not might erroneously) be used, 'a', 'an' or 'a/an' are all available. I seem to remember one such example in another thread. Commented Aug 17, 2020 at 12:00
  • Your response is absurd. You still have not shown that 95%+ of Anglophones pronounce it in any specific way, but even if you somehow could show such statistics, that still wouldn't make it the "correct" way, and thus, your argument that any other way should be ignored and not mentioned is ridiculous. But then, I just noticed your other comments on this page, and it looks like you're a pedant who simply wants to argue with other to show how "smart" you are, so I won't be responding to any further replies from you since it would be pointless. 🙄
    – Synetech
    Commented Aug 18, 2020 at 13:21

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