I was talking to a person who said that there were only two. I think she said that the "ou" in house is one of the two.

I told her that the way the letter "i" is pronounced is a diphthong, and she said it wasn't. She said it was just one vowel, "i" and that that was that.

She said she studied phonics and was writing her thesis (on child development, I think) on this kind of stuff. She said her book said there were only two diphthongs and that I was wrong.

So, how many are there? I told her I think there are probably more like ten. I thought of six immediately, but she said they weren't diphthongs because her book didn't say they were.

  1. "i" in time
  2. "i" in bite
  3. "o" in bone
  4. "a" in bane
  5. "oi" in boink
  6. "ou" in house
  • 2
    Every accent of English has its own diphthongs (and i as in the 'time' is a diphthong in every accent I have ever heard).
    – JAM
    May 23, 2012 at 3:50
  • 1
    "phonics" != "phonetics". Don't worry about it too much... May 23, 2012 at 4:54
  • 1
    @JAM: Southern AmE characteristically monophthongizes /ai/ to /a/: "I like to iron" is standardly /ai laik t aijrn/ but in SoAmE is /a lak tarn/ (more or less).
    – Mitch
    May 23, 2012 at 12:22
  • @tchrist, I've never seen a reputable phonetician argue that "the phonemic diphthong set is pretty fixed." What exactly does it mean, set? The number of diphthongs? Contrastive pairs? Set where? By whom?
    – Alex B.
    May 23, 2012 at 18:12
  • 1
    @NeilCoffey I told her I studied phonetics, and she said, "phonics, phonetics, same thing. What's the difference?" I guess you just can't ever be right with some people. Oct 3, 2012 at 23:26

5 Answers 5


Certainly the i in words like bite and fright represents an /aɪ/ diphthong.

Phonemically, I come up with these:

  1. /aɪ/ as in price, my, high, flight, mice
  2. /aʊ/ as in mouth, now, trout
  3. /eɪ/ as in face, date, day, they, grey, pain, reign
  4. /ɔɪ/ as in choice, boy, hoist
  5. /oʊ/ as in goat, toe, tow, soul, rope, cold
  6. /juː/ as in cute, few, dew, ewe
  7. /jə/ as in onion, union, million, scallion, scullion

Most examples are taken from here. What those all actually work out to phonetically varies a great deal across dialects and speakers. For example, many and perhaps even most North American speakers raise the /aɪ/ in tight to [ʌɪ], but not the one in died. You may wish to check out SoundComparisons.COM, where you can both see and hear the phonetic transcriptions for speakers of many, many different dialects, including words like four, hear, eight, cold, cow, fight.

You could also analyse words like way, yay, wow, yow as triphthongs if you really wanted to, although we don’t tend to do so in English. Instead they tend to have an initial /w/ or /j/ followed by a diphthong in normal notation. (In Spanish though they’d be considered triphthongs, as in cambiáis, which has just two syllables, cam- and -biáis.)

Non-rhotic speakers claim to have others, but I have trouble thinking of those as diphthongs myself. I always analyse diphthongs as having a principal vowel to act as the syllabic nucleus and then a glide either before or after it. If the glide comes before the main vowel, as in /jə/, /juː/, it is a rising diphthong, and if the glide comes after the main vowel, as in /aɪ/, /eɪ/, /aʊ/, /oʊ/, /ɔɪ/, it is a falling diphthong. (Some people consider only the falling ones “real” diphthongs. I’m not sure why, since million has only two syllables for me, not three.)

I know of no diphthongs in English that have no glide in them, although whether you write your glides with /j/ and /w/ or as semivowels makes no great difference. This leads to alternate transcriptions, as in /eɪ/ for /ej/, and /aʊ/ for /aw/.

If there is no glide, I don’t count it as a diphthong. That means that I don’t read /ʊə/ as a single syllable. Rather, it has two syllables, as in the programming language named Lua /ˈlʊːə/. I guess I might write that /ˈlʊː.ə/ if I thought people might misunderstand me. And no, it is not homophonic with monosyllabic lure /ˈl(j)ʊːɹ/.

Non-rhotic speakers sometimes analyse words with words with ‹r› in them as diphthongs, where they substitute /ə/ for /ɹ/, but since that’s not a glide, it’s not going to make a new diphthong in my book; it might make a new syllable, though. Even though I say fire /faɪɹ/, I realize that they say /faɪ.ə/. For me that would then rhyme with the disyllabic maya /ˈmɑjɑ/, /ˈmaɪ.ə/, although it becomes challenging to assign the /j/ to one syllable or the other. I don’t see people writing fire /ˈfajəɹ/, but at least then it would seem like two syllables. But you end up reassigning the glide and changing the word from having an /aɪ/ diphthong in the first syllable to having a /jə/ syllable in the second.

For the record, here’s how I see the following r-bearing words:

  • bearer /ˈbe(ɪ)ɹəɹ/
  • tourer /ˈtʰʊɹəɹ/
  • nearer /ˈniːɹəɹ/
  • curer /ˈkʰjʊɹəɹ/
  • layer /ˈleɪ.əɹ/, /ˈle.jəɹ/
  • lair /leɪɹ/
  • fiery /ˈfaɪɹi/ (two syllables), /ˈfa.jəɹi/ (three syllables)
  • fairy /ˈfeɪɹi/
  • Faëry /ˈfe.jəɹi/ (for trisyllabic rhymes in poetry)
  • more /mo(ʊ)ɹ/, /mɔɹ/
  • mower /ˈmoʊ.əɹ/, /ˈmowəɹ/

In that analysis, ‹r› is never part of a diphthong because /ɹ/ is not a glide, and if you write it as a schwa, you’ve likely introduced another second syllable. Non-rhotic AmE speakers (such as those from the South) always sound like they have have more syllables in their words to those of us from the North. The joke is there is no such thing as a one-syllable word in “Suthun”. For example, more is one syllable in the North’s /mo(ʊ)ɹ/, but two in the South’s /ˈmowə/.

Lastly, I realize that you can write ‹-er› as /ɚ/ or /ɹ̩/, as in murder written as either /ˈmərdər/ or /ˈmɝdɚ/. The problem is that we have only two rhotacized IPA symbols, stressed /ɝ/ and unstressed /ɚ/; for anything else that you want rhotacized, you have to use U+02DE MODIFIER LETTER RHOTIC HOOK, which doesn’t look so hot in most fonts, and doesn’t count as a combining character.

  • 3
    I believe the exact number varies by region. Certainly, speakers in my region pronounce "goat" and "soul" differently; so I know I have at least seven.
    – user16269
    May 23, 2012 at 6:30
  • 1
    @Danielδ To me, same is just say with an m tacked on.
    – tchrist
    May 23, 2012 at 16:22
  • 1
    @Daniel δ I'm surprised you don't pronounce a diphthong in "same". Your profile says your from Pennsylvania. I would have guessed you might be from Scotland or Ireland. I have a friend from Lancaster and his pronunciation doesn't differ significantly from mine. I have to wonder if you're just not hearing the diphthong, as a lot of Americans have a hard time with perceiving diphthongs at all (including the person I describe in my question, actually, who didn't hear the letter "i" as a diphthong). May 24, 2012 at 22:55
  • 1
    @DanSheppard Did you perhaps mean goal and soul? Goat ends with /t/ but soul ends in /l/, so I don't know how those could ever rhyme, even if they share the vocalic part of their rime. It’s a long topic, but liquids like /r/ and /l/ lend themselves to things like L-vocalization and epenthetic-schwa insertion, and diphthongs smoothening into monophthongs. So you can find accents with mergers where you don’t otherwise expect them, like homophones in tsar–sire–sigher or rhymes in mile–dial, fool–jewel.
    – tchrist
    Nov 5, 2022 at 17:09
  • 1
    @DanSheppard There is no [əʊ] vowel in North American English. Except when alone at the end of a word, the goat vowel [ow] is often a plain monophthong [o] here the way it is in Scottish English, and most of us have the same vowel in soul. Certainly we all have the same abstract phoneme from the GOAT lexical set. But some have pre-L breaking and produce ['sowəɫ] for soul instead, something which often sounds like it has two syllables for those of us who don’t have that accent. You might enjoy this.
    – tchrist
    Nov 5, 2022 at 21:21

Here you can find a chart of the 44 English phonemes.

Here you can find a chart of the eight diphthongs. Clicking on each one will get you a huge list of examples.

  • /eɪ/ as in day, pay, say, lay. (Examples)
  • /aɪ/ as in sky, buy, cry, tie. (Examples)
  • /ɔɪ/ as in boy, toy, coy or the first syllable of soya. (Examples)
  • /ɪə/ in beer (the drink), pier, hear. (Examples)
  • /eə/ as in bear (the animal), pair and hair. (Examples)
  • /ʊə/ as in tour, poor (talking posh!) or the first syllable of tourist. (Examples)
  • /əʊ/ as in oh, no, so or phone. (Examples)
  • /aʊ/ as in all the words of "How now brown cow!" (Examples)

Help on how to pronounce the different sounds.

  • Any comment from those who has voted negative ? May 23, 2012 at 12:37
  • 2
    @speedyGonzales, there is nothing wrong with your answer. You gave a list of diphthongs commonly recognized by phoneticians for RP dialects. phonetics.ucla.edu/vowels/chapter3/bbcenglish.html
    – Alex B.
    May 23, 2012 at 18:26
  • Could you please repair / replace the links you give, and add attributions, speedy? Also, please note that this one reference work isn't necessarily the final word on the actual situation, but rather one school of thought. Oct 23, 2019 at 11:45

In its current form, this question cannot be answered. The number of diphthongs varies from dialect to dialect.

For example, the word "four" in RP used to be pronounced as "foah", with a diphthong. Now the current RP form is "fo:" (long o). Or I say "sure" as "shuah", but there are many English speakers (in the UK) who say "sho:" (long o).

  • 1
    Once again, it depends on your dialect and your definition of a diphthong, whether you recognize triphthongs etc. As for the words "boa" and "Samoa", three major pronunciation dictionaries (EPD17, LPD3, and ODP) say that there is "oh-ah" (and thus, LPD3 marks "boa" as disyllabic and "Samoa" trisyllabic), just like the way I pronounce them. I understand that you pronounce them differently, that's fine (see my answer above about the number of phonemes in different dialects). As for "foah", it's a well known fact - see phon.ucl.ac.uk/home/wells/rphappened.htm (Merger of /ɔə/ and /ɔː/)
    – Alex B.
    May 23, 2012 at 16:07
  • 1
    @tchrist, I don't expect you to apply rules of your dialect to someone else's dialect. That'll be absurd. In your dialect, there is no "uah" (unlike in some RP dialects) => no "uah" diphthong in your "sure" and "poor". However, it doesn't mean that no one should have the uah diphthong in their dialect.
    – Alex B.
    May 23, 2012 at 18:09
  • 1
    @tchrist, "I do not recognize a schwa as a valid off-glide in a falling diphthong." Now your position is clear to me.
    – Alex B.
    May 23, 2012 at 18:55
  • 1
    Sure, you can think that if you want. My point is that your analysis is one out of many.
    – Alex B.
    May 23, 2012 at 19:35
  • 1
    I think the strict definition of a diphthong, triphthong, etc., essentially has to do with syllabicity. And so I think it is pretty useful to think of prosody. Roach, Hartman, and Jesus Christ can all claim that "boa" is monosyllabic, but I'm pretty sure Tennyson would count "boa" as having two syllables, the "bo" (with diphthong) and the "a". And "four" would depend on his pronunciation, with the version with the final schwa certainly having two syllables. The "owah" in "fowah" is not a diphthong, because no one perceives it as a single beat. I think tchrist is right on this one. May 24, 2012 at 22:47

There are ten diphthongs in Hollywood (NA) English where two sounds (a vowel followed so closely by a consonant they in effect make one vowel sound). The English Phonetic Alphabet (EPA) notation describes this clearly:

  • long a /Ay/ – great, made, day, hey, rain, eight, chaos, suede, gauge …
  • long e /Ey/ – meat, we, tree, peace, piece, quay, ski, naive, suite …
  • long i /Iy/ – my, eye, aisle, knife, pie, find, I, choir …
  • long o /Ow/ – go, know, boat, toe, goal, brooch, sew, bologna …
  • long u /Uw/ – two, you, who, due, suit, new, cool, ewe, queue, lose …

You can probably see the pattern here – long vowels are long because there are two sounds in them.

Two more that could also be considered long for the same reason are:

  • /Oy/ as in boy, noise, royal and buoy
  • /Aw/ as in owl, house, drought

The three r vowels were a vowel plus r make a distinct new sound:

  • /Ar/ – charcoal, park, heart, R
  • /Er/ – purple, first, word, were, heard
  • /Or/ – orange, four, more, war, door
  • Here is a link to the English Phonetic Alphabet (EPA) (PDF) which seems to be what the poster is referring to. Apparently it is a teaching device for ESL.
    – MetaEd
    Aug 28, 2012 at 17:13
  • 2
    The poster seems to have created the English Phonetic Alphabet. It might be a fairly accurate representation of her Southern California accent; it certainly has a number of traits consistent with English spoken in that area. Aug 30, 2012 at 3:05

First I learned diphthong from my Shorthand school, where we were taught only four diphthongs according to Sir Issac Pittman's Shorthand, quoting the definition,
"A union of two vowel sounds in one syllable.” (Prof. Sweet). They are, I, OW, OI, U, formed in the following way:

a + i = I - like pipe, pike, etc. a + ŏŏ = Ow - like couch, mouth, etc. aw + I = Oi - like boy, joy, etc. i + oo = like due, few, etc.

Pittman's Shorthand also talks about triphones, a three vowel sound i.e. diphthong + any vowel, as used in: Diary, dialogue; Viola, towel; Power, boyish; Duet, strenuous, etc.

  • 3
    Hello, Ram. You can see that there are different and contradictory answers here; possibly, this is a convenient 'reduced set'. More comprehensive than OP's acquaintance's set of two, but not as comprehensive as others given. Oct 23, 2019 at 11:33

Not the answer you're looking for? Browse other questions tagged or ask your own question.