Pronouncing ISO

Noumea

For a long time I thought that ISO was pronounced as the separate letters of the word; that is, "I-S-O." (I think that for me, this was a carryover from, "ASA," which was spoken as the three separate initials of the American Standards Association. Showing my age here a bit.)

Then, I heard others pronouncing it as, "EYE-so." That didn't seem right to me, so I started looking around the web and found conflicting advice.

ISO coordinates standards for all manner of things, but this discussion is about what used to be the convention for describing film speed (sensitivity), but is now sensor sensitivity.

Some were suggesting that ISO was an acronym from the name of the organisation — the International Standards Organization. A nice theory, except that their name is actually the International Organization for Standardization — those initials would be IOS.

To resolve the issue I devised a cunning scheme. I went to the ISO videos produced by the organisation itself to see how they pronounced it:

"EYE-so," it is.

Turns out I didn't need a cunning scheme. The ISO media page says this about their name:

Our name
From the Greek isos, meaning equal. Whatever the country, whatever the language, the short form of our name is always ISO.