"ISO 14443" is a kind of IT technical standard, but I do not know how to pronounce it.

Should it be pronounced as:

"I S O one four four four three"?

I think this sounds a little weird..

Is there some trick for pronouncing relayed numbers like the above?

  • Welcome to English Language and Usage. Yes, there is a psycho-linguistic term called "number chunking", but I am not sure if it works in this context of ISO numeration. Jul 4, 2017 at 6:17
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    ISO should be ’eye-so’ and the number will stated however rolls off the tongue the easiest usually with the least number of syllables. one four four four three is 5 syllables. So is fourteen four four three. Fourteen four forty three is six but might be easier to say for some people. So i’d pick whichever you like of those. I work with ISO two six two six two snd that’s how we say that one. But others like IEC 61508 are Eye-Ee-see sixty one five oh eight. It comes down to how ever you can spit it out the fastest.
    – Jim
    Jul 4, 2017 at 6:35
  • @Jim I have worked with different ISO over the years, including 9000, 9001, and COPC 2000, as well as the standards for photography replacing the ASA standards, and we always said ISO letter by letter. I am hearing recently that people are pronouncing it the way you suggest, but it is weird to me (but makes sense). Jul 4, 2017 at 6:46
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    @Cascabel - Interesting. I’ve never heard ISO9000 any other way than Eye-So nine thousand ( and nine thousand one)
    – Jim
    Jul 4, 2017 at 6:48
  • What I hear these days more like 'ice-o' than 'eye-so' , but that may be just an accent difference (Scotland). The number i would group as one, triple-four, three.
    – Spagirl
    Jul 4, 2017 at 6:55

1 Answer 1


Working with various nationalities around ISO-related problems, I hear a few different patterns.

ice-o for ISO (with the c being rather a z, like in German's ach so (see comments)) is rather the norm but the number varies:

  • nine thousand for 9000
  • nine thousand one for 9001
  • twenty seven thousand for 27000 (which is not a standard but a series, usually written as 2700x, and pronounced twenty seven thousand series or twenty seven x series)
  • twenty seven o o one for 27001
  • twenty seven ten for 27010
  • 1
    In the US, I hear I-S-O or ice-o (with the "c" being an "s" sound, as in isometric.) Jul 4, 2017 at 17:28
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    I've never ever heard izo (in the UK). Perhaps it's izo in non-English-speaking countries.
    – Andrew Leach
    Jul 4, 2017 at 18:18
  • @AndrewLeach: I was looking for a sound between c and z, closer to c, like isometric from the comment above.
    – WoJ
    Jul 4, 2017 at 18:24
  • @WoJ I don't know where you're from, but isometric has the /s/ sound of ice. There is no hint of voicing at all. It's exactly the same with ISO.
    – Andrew Leach
    Jul 4, 2017 at 18:25
  • @AndrewLeach: everybody is now watching me as I keep pronouncing "iso". And yes you are right, this is a "c". I am French, the impression of a "z" was probably coming from there.
    – WoJ
    Jul 4, 2017 at 18:55

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