UK vs US spelling

Back in 2005, I wrote up my study of US and UK spelling differences and published a comprehensive* list. Over the next 8 years, it’s by far the article that I’ve had the most feedback on, most of it noting one or two spellings that I missed. I eventually stopped updating the page, but since I continue to get notes, I’ve decided to do a full update and present this as a central repository for the list in an easier-to-read format.


* It would be impractical to try to offer a truly comprehensive list of any words like this, since you can make a couple of different verb forms out of almost any noun, a couple of different nouns out of nearly any verb, etc. So capital can become capitalize and capitalizes, then capitalization and capitalizing, then capitalizations and capitalizings, and even capitalizationing and capitalizationings. And then you can negate or reverse them: decapitalizationing, recapitalizationing, pseudocapitalizationing, etc. This is why any estimates of total number of words in the language or someone’s vocabulary are fairly meaningless.

I count about 1,800 of the little buggers, roots and derivatives included. That’s a lot of differences, but they break down into ten or eleven types:

  1. -ise vs -ize
  2. -ll- vs -l-
  3. (final -l vs final -ll)
  4. -ae- vs -e-
  5. -oe- vs -e-
  6. -our vs -or
  7. -tre vs -ter
  8. -gramme vs -gram
  9. -logue vs -log
  10. -ence vs -ense
  11. miscellaneous

Why list all 1800 differences? Why not just list root words? Sometimes, the difference lies not in the root (chanel, travel) but in the derivative (chanelling/chaneling, travelling/traveling). Or the difference is in the root (glamour/glamor, enthral/enthrall) but disappears in the derivative (glamorous, enthralling).

Also, the purpose of this list is to be a comprehensive collection that may come in useful if you find you need to “Americanize” your British spelling or “Briticise” your American spelling. A root-only list would not only require more work for me (to cull the derivatives) but, for anyone wanting to actually use the list programmatically (in a Word substitution macro, for example) more work to recreate all the derivatives.

In each sub-headings below, the UK spelling is first, then the US spelling.

-ise vs -ize

This includes words like agonise and terrorise as well as oddballs analyse and paralyse. This is the big dog. It covers close to 900 words. However, there are plenty of words that Americans spell -ise that don’t have the meaning “to make or create X,” including surprise, advertise, improvise. And then there’s televise, which does mean “to make into a television broadcast.”

Note that the origin of the -ise and -ize endings are different.

-ll- vs -l-

This is a strange category that actually encompasses -ller, -lling, -lled, and related constructions. It’s big—about 140 words—but very inconsistent. UK spellings like funnelled, controller, and jewellery fit the category but don’t look too odd to Americans because of enrolled, fulfilled, and similar words. Panel follows this form with paneled in the US and panelled in the UK. However, it’s just the opposite for empanel. It becomes empanelled in the US and empaneled in the UK! And, as any frequent flier knows, cancelled and canceled exist pretty much equally in US English.

(Final -l vs final -ll)

Call it a small sub-category or a call it a communist plot, words that actually end in L follow a contrary rule to the one above. Words that end in -ll in the US end in -l in the UK. So Yanks write appall, instill, and enroll, while Brits write appal, instil, and enrol. Both write awful, harmful, stressful, etc. despite the obvious connection to full.

Before you say, “Aha! Americans double the L on the end when it’s a two-syllable word with the accent on the second syllable!” feast your eyes on cartel and canal—but those are nouns, silly!—and excel, propel, and repel—well, okay, those are verbs. Brits write fulfil, but also refill. To quote the great English poet Taupin:

It’s sad. So sad. It’s a sad, sad situation. And it’s growing more and more absurd.

-ae- vs -e-

Aeon, haemorrhage, and paedophile look funny to Americans, who are used to seeing eon, hemorrhage, and pedophile. They seem old-fashioned or even ancient. They come from Latin, of course, and the vowel usually makes the long E sound (altho Americans often let it drop to short E). About 70 words fall into this category. Even so, Americans write aerodynamics (and other aero- words) and sometimes archaeology and aesthetic instead of archeology and esthetic—even tho you won’t see one writing anaesthetic like the Brits.

-oe- vs -e-

Similar to -ae-, -oe- words like foetal and diarrhoea look strange and foreign to Americans. The -oe- nearly always makes the long E sound (manoeuvre is an exception). This category includes about 25 words. On the other hand, Americans generally write subpoena, amoeba, and onomatopoeia, even tho valid non-oe- constructions exist (that is, they are valid but not preferred).

-our vs -or

The “cosmetic U,” as linguists call it, comes from Old French and wore out its welcome early. Americans have done without it in words like colour and favour for a long time, but a few examples linger on: Americans write glamour. About 150 words fit in this category.

We might expand this category slightly to include mould, moustache, and similar words.

-tre vs -ter

Some Americans love to affect the Anglo-French -re spellings for centre and theatre, yet wouldn’t be caught dead writing kilometre or lustre. This is probably the best-known difference, at least among Americans, yet only about 40 words fall into the category, most of which are derivatives of metre and litre.

We might broaden this category slightly to include calibre, manoeuvre, sabre, sepulchre, sombre, and their derivatives.

-gramme vs -gram

This includes programme and kilogramme. Programme happens to be changing to the American spelling, largely influenced by the term computer program and other -gram words (about 17). Aside from it and aerogramme, only metric system words fit this category. The total is about 16 words.

-logue vs -log

The Brits still stick to the old spellings of catalogue and monologue. These are considered acceptable to Americans, but a bit dated. Americans have a tough time deciding to write travelog, tho, or cataloging rather than cataloguing. Only about 15 words fit in this category.

-ence vs -ense

An even smaller group than the previous, the -ence root words number just nine: defence, licence, offence and their ilk. There are nearly 200 valid -ence words in US English. Why these few would be singled out for change is unclear. Fewer than 20 -ense words are found in both types of English (sense, dense, immense, etc.).

In UK English, license is the verb while licence is the noun, whereas in US English, license does double duty. Interestingly, this is somewhat similar to the difference between advice and advise, but these are pronounced differently.


A number of other spelling differences don’t fall into any of the other categories.

  • aluminium vs aluminum (this is due to historical happenstance)
  • behoves vs behooves
  • bevvy vs bevy
  • cheque vs check
  • cypher vs cipher
  • connexion vs connection (connexion is dying out in the UK)
  • draught vs draft
  • gaol vs jail (gaol is largely converted to the US spelling, even in England)
  • omelette vs omelet (you’ll see both in the US)
  • plough vs plow
  • tyre vs tire
  • yoghurt (and even yoghourt) vs yogurt
  • judgement vs judgment (you’ll see both in the UK)
Americans want to put the E in there, but their spell-checkers tell them not to. Brits often do put an E in there, altho I’m told this is not necessarily standard UK English either.
  • practise (verb) and practice (noun) vs practice

Special oddities

In the course of studying the differences between US and UK spelling, I’ve come across a few peculiarities of interest.

  • Both US and UK prefer glamour (but US accepts the non-preferred glamor). But both also prefer glamorous to glamourous.
  • Both US and UK insist on Caesar, but US prefers cesarean to caesarean.
  • The use of disc vs disk is hopelessly confused. Both insist on disc jockey and disc brakes. But both also insist on floppy disk and hard disk. In general, UK prefers disc and US prefers disk, but the spelling of the expanded form of CD depends mainly on whether you are talking about music (compact disc) or data (compact disk).
  • US insists on disheveled, initialed, and similar single-L spellings while UK insists on dishevelled, initialled, etc.
  • Full is the only word in US or UK English that ends in -full. Related words are always spelled with a single L: handful, teaspoonful, artful, successful, etc. (And, as noted above, US insists on fulfill while UK insists on fulfil.)
  • Smidgen, smidgeon, and smidgin are all valid variants in US and UK English (with smidgen being preferred in both).
  • “Fraternal twin” words like dreamt vs dreamed, leapt vs leaped, and speciality vs specialty are treated as entirely different words here, since some are sometimes found in both US and UK English.

51 thoughts on “UK vs US spelling”

  1. You have the verb license and noun licence mixed up.

    ” Some Americans love to affect the Anglo-French -re spellings” – surely you mean effect?

    Excellent article though… Added to my favourites.

    1. RSP, I think you are probably wrong in this case, though I know where you’re coming from:

      it is certainly possible, linguistically speaking, to put French spellings “into effect” – and thus to “effect them”;

      but, in this case, I think Derek meant that use of the European spelling of “theatre,” for example, would be considered an “affectation” for someone from the States. I might, for example, “affect a French accent,” though I am not French. I suppose if I were, then I could “put my French accent into effect.”

      If you like, you and I could now reopen that debate about the difference between affect and effect – which never seemed to puzzle English writers on either side of the Atlantic until the twenty first century, since when it has confused an entire young generation. I blame teechers.

      Sometimes, thinking about things too much is what starts all the confusion (eg., “shouldn’t there be an apostrophe in its?”, etc.)

  2. Thanks regarding license/licence. As a verb, “affect” means to put on falsely (an “affectation”); “effect” means to make happen (“effect an escape”).

  3. It should be pointed out that the ‘ise’ vs ‘ize’ difference is not as simple as UK vs. US. Both are used in UK English, and in fact, most of the mainstream (particularly academic) publishers will use ‘ize’.

    1. Agree. UK english is split between ‘ise’ and ‘ize’ spellings, each backed up by the Oxford and Cambridge schools, respectively.

  4. A couple of others I can think of:

    British American

    bowlder boulder (a large rock)
    burthen burden

    1. Not true – these are archaic versions of English, not used since the 19th century…that’s a totally different field. This is about the modern English/American language.

  5. I just thought I’d add as a brief comment something that I remember from my school days, drilled into me by my zealous English techer more than half century ago. In disyllabic words ending in VC, the final C had to be doubled when a suffix was added (eg. occur – occurred, occuring) except when the stress fell on the earlier syllable (e.g. open – opened and not *openned). I was also told that the Americans, thus were more correct in many such cases as they often stuck to the rule.

  6. Re earlier comments
    It is frowned upon to ever use the suffix -ize in Standard English.
    Similarly, the use of “effect” as a verb is an Americanism and is not in common usage within the English vernacular.
    As a Brit, I am also ashamed to admit that the acknowledged change from sulphur to sulfur is actually correct although I am still baffled by the American aluminum – a mispronunciation and presumably subsequent phonetic spelling error.

    1. I suppose it depends on who is doing the frowning, but I’ll take your word for it it that “-ize” is an Americanism creeping into UK English with some resistance. American “aluminum” is the result of a very understandable historical happenstance, but thank you for assuming Americans the worst.

    2. Aluminium was discovered by a Brit and named according to the usual rules of naming new elements etc. When the US put it into their newly published dictionaries, they accidentally missed out the second ‘i’. As the cost of recalling and reprinting the error wasn’t acceptable, it was left in…a simple error, a simple financial choice and there you have the difference 🙂

    3. It’s silly nonsense to say that ‘ize’ is frowned upon in ‘Standard’ English (whatever that means). Just read what the Oxford English Dictionary has to say about preferring ‘ize’ to ‘ise’!

    4. I would like to agree with “spellitright” because I grew up near Penzance (relevant in a moment). But the historical record shows that Sir Humphrey Davy (the “Brit” discoverer – from Penzance) himself used “aluminum” for the first five years (1807-1812), only adding an ‘i’ later and reluctantly. On the other hand, Americans haven’t been even less consistent. For nearly all of the 19th century Americans used both with “aluminium” (Br.) slightly ahead of “aluminum” (Am.). Even two Noah Webster dictionaries (e.g. 1915 edition) listed only the British spelling. But in the 20th century, American taste changed and they reverted back to what is (unfortunately for me and spellitright), the ORIGINAL British spelling of “aluminum” without a second ‘i’.
      I grew up knowing this – and hearing it again every time we passed his statue. But here’s my recent source:

  7. British is not the only English

    Australian spellings use only ise, isi and isa, and we don’t like the serial comma. We use practise as a verb and never spell defence with an s unless we’re feeling defensive. We also like our punctuation outside our quote marks. Yes, we eschew many things American, because one of our federal governments sold out our cultural rights a few years ago under the US’ “free trade agreement” that was foisted on many countries, and so we are (not uniquely) suspicious of that country’s creeping imperialism. South Korea is suffering similarly with a breakdown of barriers against the mudslide of American film that is fast ruining their local industry. A pity; they make excellent horror.

    We Aussies (pronounced with a z, which is pronounced ‘zed’) have good reasons to distrust Americans: they have massive military bases in our country but don’t look after our interests in other parts of the world (Australians get a disproportionate amount of lousy, dangerous assignments in Iraq, the US held our David Hicks in Guantanamo Bay on flimsy charges for years and is currently ruthlessly pursuing our Julian Assange for embarrassing the US military about its own illegal acts).

    We used to see Australian faces and hear our own accents on the tele all the time, but nowadays many of our actors have no jobs so that American advertisements can be dumped here without any Australian content (another casualty of the “free trade” arrangement that also lets US farmers be some of the most heavily subsidised in the world while insisting Australia has almost no tariffs on its goods).

    We’re not just anti-American for no reason. We don’t “hate your freedoms” – we only hate it when you smash ours to pieces.

    Editors like me cling to Australianisms. Haven’t got much else left…

    Let me suggest one I think you might have missed: curb is our verb for when we pull something in; kerb is that bit of the “footpath” (never “pavement”) that meets the road. New Zealand, South Africa and many other countries have their own versions of English too, and we need to respect and acknowledge their differences, instead of Americanising everything in case one yank whinges that they don’t know what a milk bar is.

    Thanks for listening to the lecture, and thanks for your very good site.

    Regards, Sarah Endacott.

  8. Sarah,

    The “creeping imperialism” you speak of has been going on for well over a century. All the powerful nations were/are involved; it is certainly not unique to America.

    To attack the US based on the free trade agreement is not wholly fair, as its an “agreement” which benefits both parties.

    By the way, “Americanisms” were borne of one man – a fellow named Dewey who desired to spell everything based on its sound. He changed the spelling of his own first name to Melvil. He was a man of economy, and believed in economical and simplified spellings. I don’t agree with him, but that’s the history. Americans have no wish to take away your Aussie-ness.

    Also, 2500 marines are not “massive military bases” in any country, and is a particularly tiny number when speaking of US’ installations. Here’s a link to an Australian newspaper regarding US military in your country, and just so you know, it has punctuation inside the quotes, and an interesting ‘too’ which ought to be ‘to’ – so I’m not sure anyone is perfect anywhere.


  9. Wow. And all this time, I, as a dimwitted American, thought that our two cultures got along . Nice to know another place in the world hates us.

    Let me sneak a secret to you… We like that you do things different. Doing things different (even when it is just spelling) is something Americans can respect. Our political leaders, not so much… but, when we take a vacation the last thing we want to see is another fucking McDonalds.

    1. Perhaps this will be a bit more helpful. You can use an adjective to modify a noun (example red balloon). But with some rare specific exceptions, you cannot use an adjective to modify a verb or an adjective (or indeed another adverb). For that you must use an adverb (most adjectives construct their adverbial form by appending -ly). This is not a national variation. I understand that American informal colloquialisms often replace an adverb with an adjective for humourous effect. But the rest of your post didn’t indicate any lax humourous camaraderie. So by rule it is “do things DIFFERENTLY” – even in America.

  10. Interesting article – I’ll check it again in more detail and maybe add a link to it on my website if that’s ok? You might also like to check out my conversion tool there (the “Briticiser”) which manages to convert most US English spellings to British English.

    I did learn quite a lot about the various forms of English (and improve my grammar!) while I was writing it, and I’m still picking up a few things (or being told about them) that it misses. One thing I did learn is that there is no correct form of English – generally use the brand of English which your readers are going to be comfortable reading. In formal use (e.g. within the EU, UN) there are style guides which tell you which form of English to use and, surprisingly often, this is British English although rules are only as good as the people who enforce them so you’ll often see a bit of a mish-mash of spellings even at the highest levels.

    I did find an Aussie English dictionary for MS Word a few years ago so I’ll try and find that again and drop a link to it on my website.

    1. Hi Paul… you mention a website… may I have the address? I am required to Anglecise documents for work and am always looking for good sites on American vs. British/UK spellings. That conversion tool that you mention sounds like it might be a great addition to my other resources! Thank you!

  11. Nice comment after Sarah Endac*nt’s contribution Webmaster! Absolutely loved it!!!
    And seems to me that Sarah is the whiner here….not us “Yanks!”
    She’s quite vitriolic concerning Americans, huh? I’m surprised because all the Aussies I’ve met have had
    wonderful, sunny personalities…so I was a bit shocked to hear that they (Aussies) “hate” us.
    Oh well…and I apologize for my immaturity in spelling Endacott’s name at the start…but not enough to
    change it back! Lol….. 😉

    Anyway, great article and I’m glad to have read it.


  12. I usually get the most confused between our vs. or. I’ve also noticed that sometimes I spell a word the British way, usually with double l or one l words, even though I prefer American.

    P.S. My teacher spells things the British way 😛

  13. This was a very interesting read. I love the way that language is fluid and how it changes over time and from nation to nation. Regardless of how we spell certain words, and the grammatical rules associated with suffixes, at least (well, for the most part) we can communicate easily. I am rather bemused however, as to how this thread got used by a few as a “hate” slinging match. Sorry U.S., not all Aussies are so angry and full of rage. By the way, Oxford and Macquarie both publish Australian dictionaries.

  14. On a somewhat related note – I’ve only recently discovered that “Z” is worth the same amount of points in American scrabble as it is in British scrabble – given that “Z’s” are far more common with American spelling it seems a little bit unfair.

    I know its quite a minor concern but I’d honestly never considered it before 😀

  15. Thank you very much indeed. This was interesting to read, usefully bookmarked as a reference, and appears accurate. With over 25 years in the UK and over 25 years in the USA, this is not just an idle pastime for me. I have noted that the CAUSES of the differences are not always simplifications (US: fulfill), the American version is not always the newer (UK: grey), and the American version sometimes drops the wrong vowel (UK: colour – no ‘o’ sound in the second syllable >> US: color).

    I take exception to the D of CD. That is always “disc”, regardless of country or the purpose of any digital data on it. I disagree with your rule of “a compact disc of music files” but a “compact disk of non-music files” (alas poor blank CD, or one with mixed content). In my considerable experience “compact disc” is close to universal (but it’s “cryno ddisg” in my native tongue).

  16. You’re killing me man. You keep using ‘tho’ instead of ‘though’. Where are you from? I’m from America. That sort of spelling is the only one I had a problem with. Jesus I had no idea it would bother me so much

    1. @Jimmy, nothing wrong with ‘tho’ … It’s a simplified and BETTER spelling that, altho more noted in the States, has been about since Middle English from Old English þā:

      c1460 (?c1400) Beryn (Nthld 55) 769: Shortly to conclude, al tho were aduersarijs To Rome in his dayis, he made hem tributorijs.

      2009, John Hough, “Seen the Glory: A Novel of the Battle of Gettysburg”, page 121:
      I wonder now when I will find time to read it but it is a treasure anyway tho heavy in my knapsack, …

      I’v been writing it since I was a teen and that was MANY years ago!

      You should be asking yourself why you’re sticking to the not-fonetic and etymological wrong tho-u-g-h!

  17. I’ve made a conscious decision to simplify those words in my personal writing and have used those spellings for many years.

    All languages change all the time. I encourage you to open your mind to the idea of changing it purposely to simplify it.

  18. In English, an apostrophe is necessary when it’s necessary but there are cases when its apostrophes should be left out. It’s these sorts of things that make English such an interesting torture device, since its rules are its downfall.

  19. LoveLove you Sarah,,

    Long live language freedoms, and oppose language and cultural imperialism, regardless of the source or couplet: UK on USA and vv., USA on OZ etc.

    So very appropriate for the Trump era as multiplied during the corona threat. Agreements seem to have no meaning to the USA anymore, cancel them all!

    I heavily believe all US occupational forces should be sent back to the self-isolating US of A, unreliable as allies or partners as they are. (Or can that be unreliebel az tha ar?)

    therefore I just use internet for that purpose, and takoe the most recdent information.
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