The main differences between US and UK English

When writing your dissertation, research paper or essay, you will have to consistently follow the conventions of a specific style of English. The most commonly used forms are American English, British English and Australian English. Although these dialects follow many of the same rules, they also have some important differences in spelling, punctuation and word choice. 

Check with your supervisor or department to find out if you are expected to use a specific style of English. If you are allowed to choose, pick the style that feels most natural to you. Make sure you set the correct proofing language for your document (in Microsoft Word, select “Review” and then “Language”).

Why is it so complicated?

After winning their independence from the British, Americans used language as a way to create their own identity. This led to many variations in spelling and punctuation, among other things. Australia also developed its own written conventions, which lie somewhere between those of the US and the UK (although they tend to be more British). Of the three, Australian English is generally the most flexible.

Bear in mind that the rules are not always very firm: there are many exceptions, and the preferred conventions are constantly changing!

Spelling

As the table below shows, the difference between UK and US spelling usually relates to just one or two letters.

USUKAustralia
uses -ize, -yze (e.g. quantize, analyze)prefers -ise, -yse (e.g. quantise, analyse), but is flexiblealmost always uses ise, yse
-er (e.g. center, meter, etc.)-re (e.g. centre, metre, etc.)British usage
uses -or (e.g. honor, color, splendor)uses -our (e.g. honour, colour, splendour)British usage
uses –ction (e.g. connection)acceptable to use –xion (e.g. connexion), but this is increasingly rareAmerican usage
prefers single consonants (e.g. canceled, targeted, appal), with certain exceptions for words in which the stressed syllable falls on the double consonant (e.g. willful)uses double consonants (e.g. cancelled, targetted, appall), with certain exceptions (e.g. wilful)British usage
often drops -e for word modifications (e.g. judge to judgment, live to livable)generally keeps e for word modifications (e.g. judge to judgement, live to liveable)keeps -e (e.g. judgement), like British; but sometimes drops -e (e.g. livable)
usually prefers -e to -oe or -ae (e.g. pediatrician, leukemia)uses -oe and -ae (e.g. paediatrician, leukaemia)British usage

The following cheat sheet outlines the preferred spelling of some words that are commonly used in academic writing.

Verbs
USUKAustralia
analyzeanalyseanalyse
apologizeapologiseapologise
capitalizecapitalisecapitalise
categorizecategorisecategorise
characterizecharacterisecharacterise
colonizecolonisecolonise
endeavorendeavourendeavour
enrollenrolenroll
fulfillfulfilfulfil
globalizeglobaliseglobalise
honorhonourhonour
hypothesizehypothesisehypothesise
inquireenquireenquire
installinstalinstall
legalizelegaliselegalise
maneuvermanoeuvremanoeuvre
maximizemaximisemaximise
minimizeminimiseminimise
moldmouldmould
neutralizeneutraliseneutralise
optimizeoptimiseoptimise
paralyzeparalyseparalyse
plowploughplough
privatizeprivatiseprivatise
randomizerandomiserandomise
realizerealiserealise
recognizerecogniserecognise
Past-tense verbs
USUKAustralia
canceledcancelledcancelled
channeledchannelledchannelled
labeledlabelledlabelled
modeledmodelledmodelled
traveledtravelledtravelled
Nouns
USUKAustralia
acknowledgmentacknowledgement(either)
aluminumaluminiumaluminium
artifactartefactartefact
behaviorbehaviourbehaviour
calibercalibrecalibre
centercentrecentre
colorcolourcolour
cooperationco-operation(either)
councilorcouncillorcouncilor
counselorcounsellorcounselor
defensedefencedefence
estrogenoestrogenoestrogen
fetusfoetusfoetus
fiberfibrefibre
flavorflavourflavour
humorhumourhumour
judgmentjudgementjudgement
laborlabourlabour
leukemialeukaemialeukaemia
licenselicencelicence
literlitrelitre
metermetremetre
neighborneighbourneighbour
organizationorganisationorganisation
paleontologypalaeontologypalaeontology
programprogramme (but program if computer-related)program
sulfursulphursulphur
theatertheatretheatre
tiretyretyre
vaporvapourvapour
Adjectives
USUKAustralia
agingageingageing
favoritefavouritefavourite
graygreygrey
livableliveablelivable
movablemoveablemoveable
orthopedicorthopaedicorthopaedic
salablesaleablesaleable
skepticalscepticalsceptical
sombersombresombre

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Punctuation

The main punctuation differences relate to single and double quotation marks and where to place other punctuation in relation to quotations.

USUKAustralia
Double quotation marks (“x”), but alternate with single for quotations within quotations (e.g. She said, “This model has been called ‘the best.’”)Single quotation marks (‘x’), but alternate with double for quotations within quotations (e.g. She said, ‘This model has been called “the best”’.)UK usage
Punctuation appears within quotation marks (e.g. “The best there is,” she said. or She said, “the best there is.”) except when punctuation emphasizes the writer’s sentence rather than the speaker’s quotation (e.g. Did she say, “the best there is”? or She told them we are “the best there is”!)Punctuation appears outside quotation marks, except when the punctuation is part of the original quotation (e.g. ‘The best there is’, she said. but She said, ‘the best there is.’; also, Did she say, ‘the best there is’? but She asked, ‘the best there is?’)UK usage

Verb conjugation

There are some differences in subject-verb agreement with collective nouns (nouns referring to a group of individual things as a unified whole) and in past tense verb forms.

USUKAustralia
Tends to treat collective nouns as singular (e.g. The team is going to winthe staff has decided)Tends to treat collective nouns as plural (e.g. The team are going to win, the staff have decided)US usage
Verbs take -ed endings for simple past tense and past participles (e.g. compel to compelled, spell to spelled, learn to learned), with the exception of common irregular verbs (e.g. take to took, hear to heard) Verbs take -ed endings for simple past tense and past participles, but with more exceptions (e.g. compel to compelled but spell to spelt, learn to learnt); irregular verbs are conjugated the sameUK usage

Abbreviations

There is also disagreement over how to use periods in abbreviations.

USUKAustralia
Most title abbreviations take a period (e.g. Doctor to Dr., Mister to Mr.Honorable to Hon., Drive to Dr.)Title abbreviations take a period only if the abbreviation does not end on the last letter of the full word (e.g. Doctor to Dr, Mister to Mr, but Honourable to Hon., Drive to Dr.)UK usage

Consistency is key

Most importantly, each individual word must be spelled the same throughout your document. However, it’s also best to avoid mixing different styles of English.

Examples:
  • The defense minister first travelled to China in 2013. (US English/UK English)
  • The defense minister first traveled to China in 2013. (US English)
  • The defence minister first travelled to China in 2013. (UK English)

In addition, the same spelling should generally be used for all forms of a word.

Examples:
  • The organization is headquartered in Osaka, but it usually organizes workshops in Tokyo. (US English)
  • The colours of the samples varied greatly, but the smallest sample was the most colourful. (UK English)
Is this article helpful?
Bas Swaen

Bas is co-founder of Scribbr. Bas loves to teach and is an experienced thesis writer. He tries to help students with writing clear and easy to comprehend articles about difficult topics.

6 comments

Martha Perry
April 16, 2019 at 10:17 AM

Your UK example for abbreviations is wrong. "Ave." for "Avenue" does indeed end with the same letter as the full word ("Av...e").

Also, those parentheticals are ambiguous: does the final period denote an abbreviation? Or does it simply denote the end of the sentence (following an abbreviation that does not take a period)?

Reply

Shona McCombes
Shona McCombes (Scribbr-team)
April 18, 2019 at 3:57 PM

Hi Martha, thanks for pointing out this error! The example has now been fixed :)

The final periods denote abbreviations. Consistent with the rest of the article, there are no sentence-ending periods in the parenthetical examples.

Reply

Ally B
February 24, 2018 at 7:48 PM

Dears,
Thanks for this. FYI - a spelling mistake (typo) appears in your first listed table:
"hypothesize | hypothesise|hyphothesise" - the third instance (Australian spelling) has an errant 'h' after the 'p'.
You're welcome!

Reply

Leon Smits
Leon Smits (Scribbr-team)
February 26, 2018 at 1:44 PM

Hi Ally,

Thanks!
We'll change that. :)

Cheers,
Leon

Reply

Francisco Sousa
February 16, 2018 at 3:50 AM

Thank this amazing thesis

Reply

Kris
June 16, 2016 at 8:00 PM

Thank you, this was amazing.

Reply

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