Usage of /i:/ ("EE-thur") and /ai/ ("EYE-thur") in Great Britain and in Canada seems to be mixed.
In the United States, the predominant usage has always been /i:/.
However, there's also a long history of /ai/ occurring among a few Americans, including Benjamin Franklin and James Fenimore Cooper in earlier times, and Franklin Roosevelt, Ronald Reagan and Barrack Obama more recently.
For many years, /ai/ was associated in the United States with British usage and, by extension, with certain elites who tried to imitate British usage.
It seems to have become more widespread in recent decades, however.
While some Americans have adopted /ai/, perhaps because they feel that it sounds sophisticated, other Americans regard it as pretentious.
Spelling, by the way, has nothing to do with the difference.
In English, the spelling ei usually represents the "long a" pronunciation (IPA /ei/), as in eight, feign , or rein .
In such words, it is derived from the Middle English /ai/ diphthong, which normally developed into the "long a" sound.
In a smaller set of words, such as receive , ei represents the "long e" sound /i:/.
It's rare for ei to represent the "long i" sound /ai/ in words that have been in English more than two or three hundred years; most words spelled with ei and pronounced with "long
i" are recent borrowings, such as Poltergeist (from German), or other words that only recently developed a standard spelling, such as heist (originally a variant of hoist ).
english.stackexchange.com/users/31058/Erik Thomas
I think the variation in British usage is almost all between users, not between examples of use.
It's mostly a regional and class distinction: I grew up saying /ˈaɪðə/, and we looked down on people who said /ˈiːðə/.
english.stackexchange.com/users/547/Colin Fine
If you listen to Ira Gershwin's lyrics, you realize that this argument has been going on for quite some time in America as well.
You say "either"
and I say "either" You say "
neither
" I say "
neither" "Either" "either", "neither" "neither" Let's call the whole thing off
The song points up for comic effect the differences between two lovers, who come from different social strata.
Although few Americans would say "potahto" or "tomahto" these days, there still remains a divide in the pronunciation of either , sometimes within the same speaker.
Many Americans, even ones who use what you call the British pronunciation most of the time, will say "eether" in constructions like "an 'either/or' proposition".
I find myself using the "ee" pronunciation most of the time, but switching to the other for emphasis: "Either you help me with this project right now
or I won't have time to help you with yours."
There are other words which are similarly split with regard to pronunciation to the extent that there is no "correct" way to say them.
Envelope comes to mind.
Many Americans pronounce the first syllable of that word to rhyme with on .
I don't think you can make any hard and fast rules; it just depends on who you are and what you grew up with.
english.stackexchange.com/users/2303/Robusto
According to The Complete Atlas Of The British Isles , "eether" is more common in the north of England and "eye-ther" in the south of England, with the Midlands and London using both.
The atlas also mentioned a THIRD way of pronouncing the word, "ay-ther", in parts of the north of England, which I suppose is now extinct.
english.stackexchange.com/users/41552/William Sitwell
I'm British and I use either pronunciation.
I can't think of any particular rule that I use either.
I would consider either equally valid.
I wouldn't say "me either"
though -
that is certainly an American term.
english.stackexchange.com/users/1725/glenatron
I'm in Canada.
Typically I pronounce it "ee-ther.
" I do notice a lot of American television dialogue uses "eye-ther," and American English has influenced Canadian English pronunciations since the radio and television age.
I say "me neither" (as in 'neether').
I never say "me either", although it doesn't really make less sense than "me neither", when properly it should be "nor I."
english.stackexchange.com/users/57407/Linguo
There are two common pronunciations of "either": British /ˈaɪðər/ and American /ˈiːðər/. If Americans are more or less consistent in this regard, then the Brits seem to be freely using both. In fact, from what I can tell, "either this or that" is more often in the first form, whereas "me either" is in the second. But I may be wrong. Is there any kind of an informal rule in the modern British English with regard to this?
Is there a rule in British English about how to pronounce "either"?
english.stackexchange.com
<american-english><pronunciation><british-english><pronunciation-vs-spelling><transatlantic-differences>
english.stackexchange.com/questions/6075
english.stackexchange.com/users/2044/mojuba
It appears that both pronunciations are used in British English and the difference may come down to geography or social class. Indeed, the variation in British usage may be almost all between users and not between examples of use. There may even be some people who mix both pronunciations depending on context. There is a difference between UK an North American use. Americans sometimes adopt the UK usage, but this can be seen as pretentious, but equally British people use both forms.Spelling has no bearing on the difference. The "ei" does not usually represent the long/ai/sound in words that have been in the language for a long time.In the UK, both variants are used. This could be a class phenomenon.Historically, this has been a discussion point with English language speakers. There are other similar words that are debated as to their pronounciation.
It appears that both pronunciations are used in British English and the difference may come down to geography or social class. Indeed, the variation in British usage may be almost all between users and not between examples of use. There may even be some people who mix both pronunciations depending on context. Usage of /i:/ ("EE-thur") and /ai/ ("EYE-thur") in Great Britain and in Canada seems to be mixed.  The variation in British usage is almost all between users, not between examples of use. It's mostly a regional and class distinction.
"Eether" and "eye-ther" can both be used. This may be down to personal choice, region or class - and some people may even use both. It appears that both pronunciations are used in British English and the difference may come down to geography or social class. There may even be some people who mix both pronunciations depending on context.
There is a difference between UK an North American use. Americans sometimes adopt the UK usage, but this can be seen as pretentious, but equally British people use both forms. Spelling has no bearing on the difference. The "ei" does not usually represent the long/ai/sound in words that have been in the language for a long time. In the UK, both variants are used. This could be a class phenomenon. Historically, this has been a discussion point with English language speakers. There are other similar words that are debated as to their pronounciation.
Usage of /i:/ ("EE-thur") and /ai/ ("EYE-thur") in Great Britain and in Canada seems to be mixed.   The variation in British usage is almost all between users, not between examples of use. It's mostly a regional and class distinction.
It appears that the pronunciation is largely mixed throughout British English speakers. It is possible that this is question of social class and may vary from speaker to speaker. It is possible that this is a regional variation. Some people may use both pronunciations depending on the context.