More specifically, I was wondering whether the schwa sound can predict which vowel to use in spelling?

For instance, does the schwa sound predict "a" spelling more than "e" spelling? I noticed that some people often misspell the word "separate" as "seperate".

UPDATE: If there is a pattern, what are the numbers of the schwa sound being a specific vowel? (i.e. schwa --> e, schwa --> i, schwa --> o, schwa --> a, schwa --> u, schwa --> y).

  • 2
    My version of separate is usually just two syllables (no schwa). And if it weren't for my browser's spell-checker I'd very likely have misspelt it anyway. But although I don't think it's a particularly useful "rule", I think you'd probably get the spelling right more often if you assumed a schwa is more likely to be represented by e than by a in the written form. Jan 31, 2018 at 17:37
  • 3
    @FumbleFingers Adjectival separate has two syllables to me; verbal separate has three. Do you have only two in both? Jan 31, 2018 at 18:12
  • @JanusBahsJacquet: Actually, now you've pointed it out to me, I realise almost the entirety of my usually just two syllables above was down to the adjective/verb distinction. I'm pretty sure I occasionally use three syllables for the adjective, but I'm absolutely certain I'd never use just two syllables for the verb form. Jan 31, 2018 at 18:21
  • @FumbleFingers Thanks for your comment/answer. The predictability would explain why people spell words like separate incorrect. Updating my question.
    – Boondoggle
    Jan 31, 2018 at 20:33
  • 1
    Interesting question. I'd certainly say it indicates points in a word where there are likely to be misspellings!
    – Noldorin
    Mar 6, 2018 at 1:57

4 Answers 4


Absolutely not. Pronunciation never determines spelling in English. Spelling has its own ancient history, one far removed from any attempt to encode pronunciation.

There are all schwas:

  • Alan
  • mountain
  • kitten
  • cetacean
  • foreign
  • satin
  • atomician
  • motion
  • lemon
  • autumn
  • Eryn
  • rhythm
  • acre
  • little

In the case of the two most commonly misspelled words in the English language, separate and occurrence, these are spelled that way because of how Latin respectively spelled sēparāre < + parāre and occurrencia < occurrentia.

The same sort of thing is true with a very great many other words in English. You have to understand their history to understand their spelling. Pronunciation is virtually immaterial.

  • 1
    Satin? That must be a pretty US-specific pronunciation. I don't know Eryn, but if that's how you spell Erin = Ireland, I can't say I've ever heard that with a schwa either. Jan 31, 2018 at 17:40
  • @FumbleFingers OED has phonemic /ˈsætn/ which may well be phonetic [ˈsɛəʔn̩] as often as not. Sounds rather like somebody sat in it. The syllabic /n/ can also be spelled /ən/. Anyway, penicilin had too many syllables. :)
    – tchrist
    Jan 31, 2018 at 17:45
  • 2
    I see penicillin also has too many l's for your taste! But that's another one that simply underscores how difficult it would be to produce a definitive answer to OP's question. Putting aside your somewhat brusque Absolutely not, it should in principle be possible to count all the words where a is enunciated as a schwa, and compare them to the same with e. Except we'd have a real hard time agreeing on things like whether or not there can be a schwa in penicillin (but I hope we're not disagreeing on how many l's it's got; even M-W has two! :) Jan 31, 2018 at 17:59
  • 1
    (Just as an aside, is virtually immaterial tautological?) Jan 31, 2018 at 18:00
  • +1 Also ___ous, __ious, and from your post, virtually, and because ! Mar 6, 2018 at 22:00

The other answers answer the question I think, but just as regards to "separate", it is possible that people who misspell it aren't predicting an "e" from the schwa sound (after all, Boondoggle's data shows that "o" would make as much if not more sense there as "e" does), but are spelling by analogy with the word/syllable "per", which is pronounced with a schwa/r-colored vowel the same way as the "par" in "separate", whereas the word/syllable "par" in isolation is not.

  • At one time, I realised that I was often misspelling "separate" because I was confusing its spelling with that of "several".
    – Colin Fine
    Mar 8, 2018 at 11:04
  • cmudict_0.7b gives for the phoneme 'P + R-colored vowel' 132 words with PAR spelling and 1,086 words with PER spelling. So, the 'P + R-colored vowel' is more than 8 times as likely to be represented by PER than by PAR spelling (in a dictionary, so not considering actually frequency of the words in a corpus).
    – Boondoggle
    Mar 8, 2018 at 18:34

The schwa predicts the spelling to some extent, although highly inconsistent in most cases.

Hanna et al. (1966) found that phoneme to grapheme correspondence is dependent upon the position of the phoneme within the syllable. An algorithm scored whether a phoneme occurred in the first, the middle, or in the final part of a syllable. For instance the word 'string' would be separated into initial: S T R, medial: I, and final: NG. The phonemes were matched to the graphemes of the words based on the Zipfian least effort principle. Based on phonological information alone about 49 percent of the 17,000 words in the corpus could be spelled correctly.

Below is a table with the 7 most popular graphemic options for the schwa sound in relation to the position within a syllable, adapted from Hanna et al. (1966, p. 59):


From this table we can calculate the schwa-letter correspondence:

O | 26.79%

A | 23.91%

I | 22.40%

E | 12.68%

OU | 5.58%

U | 4.93%

E-E | 1.67%

The schwa sound is about twice as likely to correspond to the letter "A" (23.9%) than to the letter "E" (12.7%). When the schwa is in the final part of a syllable the most probable candidate for spelling is the letter "A" (1419/3023 * 100 = 47.3%) followed by the letter "I" (1332/3023 * 100 = 44.1%). However, the probability of the schwa being an "A" in a middle part of a syllable is less than one percent (only 13 occurrences).

There's a ~99% chance that the schwa does not represent an "A" or "I" in the first or middle part of syllables. Now what does this mean in practice?

Consider the word separate.

It can be divided into seven phonemes and three syllables:

S E3 P - SWA - R A T (verb)

S E3 P - SWA - R I3 T (adj)

Six phonemes with the R-colored vowel instead of the schwa (cmudict-0.7b):

S EH1 P - ER0 - EY2 T (verb)

S EH1 P - ER0 - IH0 T (adj)

Or six phonemes and two syllables:

S EH1 P - R AH0 T (adj)

In the adjective version the second syllable may not be pronounced. In other cases the schwa phoneme or the R-vowel is used in the second syllable. When the schwa is in medial position (i.e. the middle of syllable) the predicted spelling would be an "O" (1176/2046 * 100% = 57.5%) or an "E" (420/2046 * 100% = 20.5%).

It might be useful to instruct English writers with exceptions to phoneme-grapheme correspondence, particularly schwa-A (19 words) and schwa-I (15 words).

Hanna et al. has a list of those words, some of them are questionable:

Schwa spelled "A":

  • initial position of the syllable (p. 1423): anarchist, anarchy, ballast, damask, harass, palatable.
  • medial position of the syllable (p. 1423): breakfast, canvas, canvass, carcass, compass, cutlass, encompass, pampas, purchaser, trespass, trespasser, windlass.

Schwa spelled "I":

  • initial position of the syllable (p. 1437): basil, civil, gossip, imperil, peril, vigil.
  • medial position of the syllable (p. 1437): council, moccasin, nostril, pencil, stencil, tendril, tonsil, tulip, turnip.

In some dialects a word may not actually be pronounced with a schwa such as with anarchy. And the syllabification in some cases is questionable such as with palatable. This makes it more difficult to generate a reliable spelling rule based on pronunciation across dialects.

  • 1
    Even if one were to accept the numbers, I don't see an aggregate statistical imbalance like this as any kind of useful tool for predicting spelling. It's English; there are just too many exceptions.
    – Spencer
    Mar 6, 2018 at 11:19
  • I made a mistake. The initial, medial, and final parts actually refer to the positions of occurrence within a syllable. E.g. 'string' would be separated into initial: STR, medial: I, and final: NG.
    – Boondoggle
    Mar 6, 2018 at 19:23
  • 1
    @Araucaria: Looking through the linked document, it seems initial position = no other sounds before it in the same syllable, final position = no other sounds after it in the same syllable, medial position = sounds before it and after it in the same syllable. The examples given on page 25 are "pal at a ble", "can vas", and "ca nal". But that raises the question of what syllable division method to use, since many people would divide "palatable" as "pa la ta ble" or perhaps "pal a ta ble".
    – herisson
    Mar 6, 2018 at 22:25
  • @Araucaria: I think it is clearly true that there are many more cases of "a" corresponding to schwa in open syllables than there are of "a" corresponding to schwa in closed syllables, but it's less clear that the data in the linked document is of any help in differentiating between what vowel letter to use to spell schwa if you just know the pronunciation of a word.
    – herisson
    Mar 6, 2018 at 22:30
  • I've reversed my vote. I do think it would be helpful for readers if you explained what "position in the syllable" means here (because arguably, the vowel occurs in the nucleus of the syllable in each case - but what is important here is whether there are any preceding or following consonants). Last thing, do you mean "seven phonemes and three syllables"? [ /sepərət /]. Interesting post (sorry I didn't appreciate it the first time!) Mar 7, 2018 at 17:35

In some accents, schwa is less likely to be written with "i" or "y"

This depends partly on one's accent. Some accents maintain a somewhat (although not entirely) stable phonemic distinction in some words between two types of "weak" or "reduced" vowels: a more front one, usually identified with the strong/unreduced vowel found in the word "kit" (/ɪ/), and a more central one, usually identifed with the "schwa" symbol /ə/, and often thought of as being similar to the strong/unreduced vowel found in the word "strut".

But speakers of some other accents feel that there is (at least in general) no stable phonemic distinction like this between different kinds of weak/reduced vowels. The absence of a phonemic distinction between weak /ɪ/ and /ə/ has been called the "weak vowel merger".

You can see from the discussion beneath tchrist's answer that FumbleFingers does not seem to have this merger, while tchrist does have this merger.

My understanding is that the Oxford English Dictionary (OED) uses transcriptions that assume that an American English speaker will have the weak vowel merger, but a British English speaker may or may not have the merger. The symbol /ᵻ/ is used in OED transcriptions to indicate a vowel that may be pronounced as /ɪ/ or as /ə/; in contemporary British English, this usually corresponds to a word that was considered to have "weak" /ɪ/ in "RP" English.

  • I believe the letter "i" in an unstressed syllable often, although not always, corresponds to /ɪ/ rather than /ə/ for a speaker without the weak vowel merger. The same goes for "y". The OED transcribes the verb "predicate" as "/ˈprɛdkeɪt/, U.S. /ˈprɛdəˌkeɪt/", and the verb "carboxylate" as "Brit. /kɑːˈbɒksleɪt/, U.S. /ˌkɑrˈbɑksəˌleɪt/". Word-internally, it is possible for "i" to correspond to /ɪ/ before /r/, as in "perspirate" (OED: "Brit. /ˈpəːspreɪt/, U.S. /ˈpərspəˌreɪt/") or "hydrargyrum" (OED (1899): /hʌɪˈdrɑːdʒɪrəm/).

  • The situation with "e" seems to be more complicated, but in at least some circumstances it can correspond to weak /ɪ/ rather than /ə/. The OED transcribes the verb "aggregate" as "Brit. /ˈaɡrɡeɪt/, U.S. /ˈæɡrəˌɡeɪt/". However, it seems like "e" is generally pronounced /ə/ before /r/ , even in accents without the weak vowel merger: the OED transcribes "generate" as "Brit. /ˈdʒɛnəreɪt/, U.S. /ˈdʒɛnəˌreɪt/".

  • I am not aware of any case where the letter "o" corresponds to weak /ɪ/. There might be a few, but it doesn't seem to be a regular correspondence. The OED transcribes the verb "advocate" as "Brit. /ˈadvəkeɪt/, U.S. /ˈædvəˌkeɪt/".

  • I think the letter "a" typically can only correspond to weak /ɪ/ in word-final syllables with a consonant after the "a" (such as "-ace" in "palace" (OED "Brit. /ˈpals/, U.S. /ˈpæləs/") and "-age" in "manage" (OED "Brit. /ˈrʌmɪdʒ/, U.S. /ˈrəmədʒ/"; oddly, the OED entry for "manage" says "Brit. /ˈmanɪdʒ/, U.S. /ˈmænɪdʒ/").

  • I think the letter "u" can only correspond to weak /ɪ/ in a few words, such as "minute' (OED "Brit. /ˈmɪnɪt/, U.S. /ˈmɪnt/"), but not in words like "adjuvate" (v.), which the OED transcribes "Brit. /ˈadʒᵿveɪt/, U.S. /ˈædʒəˌveɪt/" (the symbol ᵿ in OED transcriptions is a shorthand for "/ʊ/ or /ə/").

However, in an accent without the weak vowel merger, the digraphs "ir" and "yr" (with no pronounced /r/ consonant sound) can represent schwa (e.g. in "elixir", "satyr", "martyr", "confirmation").

The linked Wikipedia article about the "weak vowel merger" also mentions "The use of final /əl/ in words like evil and pencil is now extremely common in both General American and RP, to the extent that the alternative /ɪl/ can sound archaic or stilted."

Accents with the weak vowel merger

As you can see from the above, in an accent with the weak vowel merger (like the accent that the OED chooses as representative of the U.S.), schwa may correspond to any of the letters a, e, i, o, u, y (or even, as tchrist points out, a combination of multiple letters).

There is a tendency for /-ər-/ to be spelled "-er-"

The tendency that you have observed for some people to write "separate" as "seperate" may be due to a few factors:

  • The letter "e" seems to be more common than the letter "a" in general in English.

  • The spelling pattern "er" = /ər/ is fairly common. It occurs in the common suffix "-er", as well as showing up word-internally before a vowel in many words from French and/or Latin such as general, federal, mineral, lateral, literal, several, generous, numerous, moderate, operate, desperate, temperate, temperature, refrigerate, different. In fact, in non-initial syllables, the sequence "erV" was more common than many other VrV sequences in Latin words because of historical sound changes of vowel reduction that caused short vowels to change to "e" in this context. The word "separate" does not in fact come from a Latin word with a reduced vowel in the second syllable (probably due to its origins as a compound word, although I don't know the details), but an English speaker is unlikely to have an intuitive sense of which non-final syllables in words from Latin went through the process of vowel reduction and which did not.

The web page "Spelling the Vowels of English Received Pronunciation" (which seems to be based on date from one of the projects of Washington University in St. Louis’s Reading and Language Lab) has some notes that seem consistent with what I say above (there is also a link to the statistics that these notes are based on):

/ə/ as in adore


  1. <a> normally;


  1. <e> in medial syllables before /r/;



  1. <a> is by far the most common spelling for /ə/ in the general case (saliva), but 8 or 9 other spellings are also quite common, including <o> (daffodil), <er> (clever), <e> (shellac), <or> (forbid), <u> (triumph), <ar> (cellar), <re> (fibre), <ur> (pursue).


  1. This pattern depends to a large extent on the fact that Latin mostly had <e> in this position (camera, viscera). Otherwise <a> (minaret), and <o> (calorie) are quite common as well.

(bolding added by me)

So in fact, it seems like the common misspelling "seperate" may use a spelling of schwa that is in this context (before an intervocalic /r/) somewhat more common than the "a" used in the standard spelling "separate" (although the "a" spelling is also noted to be "quite common" in this context).

16 rules for going from sound to spelling for schwa in "RP"

The linked web page lists 16 total rules of thumb for spelling schwa; you can see that this is a complicated area of English spelling. Note that the analysis is of the "RP" ("Received Pronunciation") accent of English, which is "non-rhotic" ("data" and "corner" both end in schwa), so a considerable amount of the spellings that are discussed include "r". An analysis of a rhotic accent such as "General American" English would surely have significantly different results in many places.

The full set of identified tendencies for the spelling of schwa in RP, along with the explanations:

  1. <a> normally;

  2. <u> after initial /s/;

  3. <o> after initial /k/;

  4. <o> before /n/;

  5. <o> in medial syllables before /l/;

  6. <e> in medial syllables before /r/;

  7. <e> before final /nt/;

  8. <o> before final /k/, /p/, /t/, or /m/;

  9. Unspelt in final /zəm/;

  10. <u> before final <s>;

  11. <e> before final /l/;

  12. <ar> before final /d/;

  13. <er> after /t/, when word-final or preceding /n/;

  14. <er> word-finally after /d/;

  15. <er> word-finally after /ð/;

  16. <er> word-finally after /p/.


Statistics. Schwa appears only in unstressed syllables, but is very frequent there. Some care should be taken here, in that northern speech often has a full vowel where RP, and therefore this list, has a schwa.

  1. <a> is by far the most common spelling for /ə/ in the general case (saliva), but 8 or 9 other spellings are also quite common, including <o> (daffodil), <er> (clever), <e> (shellac), <or> (forbid), <u> (triumph), <ar> (cellar), <re> (fibre), <ur> (pursue).

  2. This case is due mostly to forms of the Latin prefix sub-. These forms have a tendency to be pronounced with /ʊ/ in the north. A few words in <a> (saloon) and <o> (solicit) are also found.

  3. This case is due mostly to forms of the Latin prefix con- (commence, condense). These forms have a tendency to be pronounced with /ɒ/ in the north. In other forms, the spelling <a> is most common (casino).

  4. This pattern emerges in part beceause it recapitulates the con- rules above (confide), in part because final /ən/ is disproportionately common (apron). This is only partly due to the Greek ending -on (rhododendron). The spellings <a> (pagan), <e> (token), and <er> (lantern) are also quite common. Note that no particular effort has been made here to distinguish the sequence /ən/ from syllabic /n̩/.

  5. This pattern is due mostly to an Italian diminutive pattern (tremolo); otherwise <a> (buffalo), and <e> (procelain) are quite common as well. Note that it is not unusual for vowels to disappear entirely in such words.

  6. This pattern depends to a large extent on the fact that Latin mostly had <e> in this position (camera, viscera). Otherwise <a> (minaret), and <o> (calorie) are quite common as well.

  7. This depends on a common Latin pattern (aliment, silent), but there is also a prolific competing French pattern in -ant (tenant).

  8. In general, <o> is used before word-final voiceless or nasal stops. This rule doesn't generalize to voiced stops, however; in particular, note the rule for final /d/ below. Other spellings are possible, but the default spelling <a> is surprisingly rare before voiceless stops.

  9. An exception to the general rule for final /m/ (prism, spasm).

  10. This pattern is due to the many Latin loans in -us. A more typical English spelling is with <a> (carcass, compass, terrace).

  11. -el is a common native ending, but there are also many words in Latinate -al.

  12. A few words use <o> or <a>.

  13. Although <ter> (bitter) and <tern> (lantern) are common patterns, there are also many words in <ta> (data), <tan> (titan), <tre> (centre), <tar> (altar), <ton> (carton), and <tor> (motor).

  14. <der> is most common in native words (murder), but there are many Latin and Romance words in <da> (agenda, armada).

  15. This is a particularly reliable pattern in that there are a dozen words meeting it, and no exceptions. On the other hand, most of the words are like either in being grammatical.

  16. There are only a handful of exceptions, like pupa.


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