- British English has 8 diphthongs: 5 closing diphthongs and 3 centring diphthongs.
- A diphthong is one continuous glide, not two separate vowel sounds or syllables.
- Learners often flatten diphthongs into pure vowels or split them into extra syllables.
- Centring diphthongs (near, square, cure) exist because British English is non-rhotic.
- Practising the glide in slow motion before speeding up builds accurate muscle memory.
A diphthong is a vowel sound that begins in one tongue and lip position and glides smoothly toward another within a single syllable. English relies heavily on diphthongs — they appear in extremely common words like I, my, no, go, day, and now — so mastering them is essential for natural-sounding speech, not an optional extra.
This guide introduces all 8 diphthongs of standard British English, split into closing diphthongs (which glide toward a high vowel) and centring diphthongs (which glide toward the schwa), with IPA symbols and example words for each.
1. What Is a Diphthong?
Diphthongs contrast with monophthongs, or pure vowels, which keep a single stable tongue position for the whole sound (as in the /iː/ of see or the /ɒ/ of lot). In a diphthong, the tongue and sometimes the lips move continuously from a starting quality to an ending quality within one syllable — the vowel in time, for example, starts near an open central position and glides up and forward toward /ɪ/.
A diphthong is a single vowel sound and a single syllable, even though it contains a glide between two vowel qualities. This is different from a sequence of two separate vowels in different syllables, such as the two syllables in "chaos" or "radio".
2. The 5 Closing Diphthongs
Closing diphthongs glide toward a higher tongue position — either /ɪ/ (front) or /ʊ/ (back):
| IPA | Example Words | Glide |
|---|---|---|
| /eɪ/ | face, name, say, they, late | Mid front → high front |
| /aɪ/ | price, time, my, night, buy | Open central → high front |
| /ɔɪ/ | choice, boy, noise, coin | Mid back rounded → high front |
| /əʊ/ | goat, home, no, know, soul | Central → high back rounded |
| /aʊ/ | mouth, now, out, how, town | Open central → high back rounded |
Each of these diphthongs is common in everyday vocabulary, so shortening or flattening them (a frequent learner habit) affects the clarity of very high-frequency words.
3. The 3 Centring Diphthongs
Centring diphthongs glide toward the schwa /ə/ rather than toward a high vowel. They exist in British English because it is non-rhotic: these words historically had an /r/ after the vowel, which weakened over time into a schwa glide instead of disappearing completely.
| IPA | Example Words | Glide |
|---|---|---|
| /ɪə/ | near, here, ear, idea, beer | High front → schwa |
| /eə/ | square, there, hair, care, bear | Mid front → schwa |
| /ʊə/ | cure, pure, tour, during | High back → schwa (increasingly rare; often replaced by /ɔː/ in modern British speech) |
American English does not have these three centring diphthongs — because American English is rhotic, words like near, square, and cure are instead pronounced with the vowel followed by a clear /r/ sound.
4. Common Learner Mistakes
- Flattening the glide into a pure vowel: saying a flat "eh" for /eɪ/ in face, so it sounds closer to "fess". Fix: exaggerate the glide in slow motion, clearly moving from the starting to the ending position.
- Splitting a diphthong into two syllables: pronouncing "time" as two beats instead of one. Fix: practise keeping the glide continuous and quick, within a single syllable pulse.
- Confusing similar diphthongs: mixing up /aɪ/ (price) and /aʊ/ (mouth), or /eɪ/ (face) and /aɪ/ (price). Fix: drill minimal pairs that isolate the ending position, such as "buy" vs "bough" or "bay" vs "buy".
- Under-rounding the lips on back-gliding diphthongs like /əʊ/ and /aʊ/: Fix: watch your lips in a mirror and make sure they round noticeably by the end of the glide.
5. Diphthong Minimal Pairs
These pairs help isolate specific diphthong confusions:
- /eɪ/ vs /aɪ/: bay / buy, say / sigh, way / why
- /aɪ/ vs /aʊ/: mice / mouse, tile / towel, hide / how'd
- /əʊ/ vs /ɔː/ (pure vowel): coat / caught, boat / bought, low / law
- /ɔɪ/ vs /aɪ/: boy / buy, coin / kine (rare, but toy / tie works well)
- /ɪə/ vs /eə/: beer / bear, here / hair, near / stare (approx.)
6. Tips for Practising Diphthongs
- Practise in slow motion first. Hold the starting vowel, then glide slowly toward the ending vowel, before speeding up to natural speed.
- Watch your mouth in a mirror for lip rounding on back-gliding diphthongs like /əʊ/ and /aʊ/.
- Use minimal pairs to isolate exactly which diphthong you are confusing with another sound.
- Listen actively to native speech and try to notice the glide, not just the starting sound — many learners only hear the beginning of a diphthong and miss the movement.
- Practise full sentences with several diphthongs, such as "I hope you go home now," to build natural connected-speech control.
7. Diphthongs and Word Stress
Diphthongs behave differently depending on whether they carry word stress. In a stressed syllable, a diphthong keeps its full glide and length, as in the first syllable of TABLE /eɪ/. In an unstressed syllable, however, a diphthong is often reduced toward the schwa, or replaced by a shorter vowel altogether — this is one reason unstressed grammatical endings and function words rarely contain a full diphthong. Recognising this connection between stress and vowel quality helps explain why some words that look similar on paper, such as the noun record and its related forms, can carry a full diphthong in one syllable and a reduced vowel in another.
This link between stress and diphthong strength is also why non-native speech sometimes sounds "flat": if every syllable is given a fully realised diphthong regardless of stress, the natural contrast between prominent and background syllables disappears, and the rhythm of the sentence no longer matches what native listeners expect.
Hear Diphthongs Read Aloud
Use LexFizz's free Text to Speech tool to hear any word containing a diphthong, and practise producing it with Speaking Cards.
Try Text to Speech →Frequently Asked Questions
What is a diphthong?
A diphthong is a vowel sound that starts in one tongue and lip position and glides smoothly to another position within the same syllable. Because the sound changes continuously rather than staying fixed, a diphthong is sometimes called a gliding vowel, in contrast to a monophthong, or pure vowel, which stays in one position.
How many diphthongs does English have?
Standard British English (Received Pronunciation) has 8 diphthongs: /eɪ/ (face), /aɪ/ (price), /ɔɪ/ (choice), /əʊ/ (goat), /aʊ/ (mouth), /ɪə/ (near), /eə/ (square), and /ʊə/ (cure). American English has a similar but slightly different set, most notably lacking the centring diphthongs /ɪə/, /eə/ and /ʊə/ because American English is rhotic.
What is the difference between a diphthong and a monophthong?
A monophthong is a vowel with a single, stable tongue position throughout, such as the /iː/ in see or the /ɒ/ in lot. A diphthong involves two vowel qualities produced in one continuous glide within a single syllable, such as the /aɪ/ in my, which starts near /a/ and glides toward /ɪ/.
Why do diphthongs cause problems for ESL learners?
Many languages either lack diphthongs entirely, treating vowel sequences as two separate syllables, or have a different inventory of glides than English. Learners often either shorten a diphthong into a pure vowel (saying a flat "e" instead of the glide in face) or split it into two full syllables. Both errors make speech sound less natural even when the word is understandable.
What are centring diphthongs?
Centring diphthongs are diphthongs that glide toward the schwa /ə/ sound rather than toward a high front or back vowel. British English has three: /ɪə/ as in near, /eə/ as in square, and /ʊə/ as in cure. These occur because British English is non-rhotic — historically these words had an "r" sound after the vowel, which weakened into a schwa glide over time.
How should I practise producing diphthongs correctly?
Start by saying the starting vowel position and holding it, then slowly glide toward the ending position while keeping the sound continuous rather than stopping and restarting. Practise in slow motion first — for example, for /aɪ/ in "my", hold the open /a/ position, then slowly close toward /ɪ/ — before speeding up to natural speed.
Which English diphthong is hardest for most learners?
The /əʊ/ diphthong in words like goat, home, and no is commonly difficult because many languages have a pure back vowel similar to "o" with no glide at all, so learners substitute a flat monophthong. The /aʊ/ diphthong in mouth and now is also frequently flattened into a single vowel by learners whose first language lacks a similar glide.
Do diphthongs count as one sound or two for spelling and syllable purposes?
A diphthong counts as a single vowel sound and typically forms one syllable, even though it involves a glide between two vowel qualities. For example, "time" has one syllable and one vowel sound, /aɪ/, despite gliding between two positions. This is different from two separate vowels in different syllables, such as the "io" in "radio", which forms two syllables.
Are diphthongs the same in British and American English?
Mostly similar but not identical. The quality of /əʊ/ (goat) and /aʊ/ (mouth) differs slightly between accents, and American English does not have the three British centring diphthongs /ɪə/, /eə/, /ʊə/ because American English pronounces the "r" sound in words like near, square, and cure instead of gliding to a schwa.
Can diphthongs change the meaning of a word?
Yes. Diphthongs distinguish many minimal pairs from pure vowels or from other diphthongs, such as "coat" /əʊ/ versus "cot" /ɒ/, or "boy" /ɔɪ/ versus "buy" /aɪ/. Getting the glide direction or starting position wrong can make one word sound like a completely different word.