UK vs. US English | Difference, Spelling & Examples

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
• Australian English

Although these dialects follow many of the same rules, they also have some important differences in spelling, punctuation and word choice.

NoteCheck with your supervisor 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 language for your document (in Microsoft Word, select “Review” and then “Language”).

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US vs. UK spelling

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

US
UK
Australia

uses -ize, -yze (e.g., realize, analyze)
prefers -ise, -yse (e.g., realise, analyse), but is flexible
almost always uses ise, yse
-er (e.g., theater, meter)
-re (e.g., theatre, metre)
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 rare
American 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

usually prefers one “l” to double “ll” (e.g., canceled, traveled)
uses double “ll” instead of one “l” “(e.g., cancelled, travelled)
British usage (travelling vs traveling, cancelled vs canceled)

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

Verbs

US
UK
Australia

analyze
analyse
analyse

apologize
apologise
apologise

capitalize
capitalise
capitalise

categorize
categorise
categorise

characterize
characterise
characterise

colonize
colonise
colonise

endeavor
endeavour
endeavour

enroll
enrol
enrol

fulfill
fulfil
fulfil

globalize
globalise
globalise

honor
honour
honour

hypothesize
hypothesise
hypothesise

inquire
enquire
enquire

install
instal
install

legalize
legalise
legalise

maneuver
manoeuvre
manoeuvre

maximize
maximise
maximise

minimize
minimise
minimise

mold
mould
mould

neutralize
neutralise
neutralise

optimize
optimise
optimise

paralyze
paralyse
paralyse

plow
plough
plough

privatize
privatise
privatise

randomize
randomise
randomise

realize
realise
realise

recognize
recognise
recognise

Past-tense verbs

US
UK
Australia

canceled
cancelled
cancelled

channeled
channelled
channelled

labeled
labelled
labelled

modeled
modelled
modelled

traveled
travelled
travelled

Nouns

US
UK
Australia

acknowledgment
acknowledgement
acknowledgment or acknowledgement

aluminum
aluminium
aluminium

artifact
artefact
artefact

behavior
behaviour
behaviour

caliber
calibre
calibre

center
centre
centre

color
colour
colour

cooperation
co-operation
cooperation or co-operation

councilor
councillor
councillor

counselor
counsellor
counsellor

defense
defence
defence

estrogen
oestrogen
oestrogen

fetus
foetus
foetus

fiber
fibre
fibre

flavor
flavour
flavour

humor
humour
humour

judgment
judgement
judgement

labor
labour
labour

leukemia
leukaemia
leukaemia

license
licence
licence

liter
litre
litre

meter
metre
metre

neighbor
neighbour
neighbour

organization
organisation
organisation

paleontology
palaeontology
palaeontology

program
programme (but program if computer-related)
program

sulfur
sulphur
sulphur

theater
theatre
theatre

tire
tyre
tyre

vapor
vapour
vapour

Adjectives

US
UK
Australia

aging
ageing
ageing

favorite
favourite
favourite

gray
grey
grey

livable
liveable
livable

movable
moveable
moveable

orthopedic
orthopaedic
orthopaedic

salable
saleable
saleable

skeptical
sceptical
sceptical

somber
sombre
sombre

US vs. UK punctuation

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

US
UK
Australia

Double quotation marks (“x”), but alternate with single for quotations within quotations

• She said, “This model has been called ‘the best.’”

Single quotation marks (‘x’), but alternate with double for quotations within quotations

• She said, ‘This model has been called “the best”’.

UK usage

Punctuation appears within quotation marks…

• “The best there is,” she said.
• She said he is “the best there is.”

… except when punctuation emphasizes the writer’s sentence rather than the speaker’s quotation

• Did she say, “the best there is”?
• She told them we are “the best there is”!

Punctuation appears outside quotation marks…

• ‘The best there is’, she said.
• Did she say, ‘the best there is’?

…except when the punctuation is part of the original quotation rather than the speaker’s sentence.

• She said, ‘the best there is.’
• She asked, ‘the best there is?’

UK usage

US vs. UK 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.

US
UK
Australia

Tends to treat collective nouns as singular.

• The team is going to win, the staff has decided

Tends to treat collective nouns as plural.

• The team are going to win, the staff have decided

US usage

Verbs take -ed endings for simple past tense and past participles…

• compel to compelled
• spell to spelled
• learn to learned

… with the exception of common irregular verbs

• take to took
• hear to heard

Verbs take -ed endings for simple past tense and past participles, but with more exceptions…

• compel to compelled
• spell to spelt
• learn to learnt

… and irregular verbs are conjugated the same

• take to took
• hear to heard

UK usage

US vs. UK abbreviations

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

Consistency is key

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

Examples: Mixing different styles of English

• The

  defense

  minister first

  travelled

   to China in 2013.

• The

  defense

  minister first

  traveled

  to China in 2013.

• The

  defence

  minister first

  travelled

  to China in 2013.

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

Examples: Mixing different styles of English

• The

  organization

  is headquartered in Osaka, but it usually

  organises

  workshops in Tokyo.

• The

  organization

  is headquartered in Osaka, but it usually

  organizes

  workshops in Tokyo.

• The

  organisation

  is headquartered in Osaka, but it usually

  organises

  workshops in Tokyo.

If you use our proofreading and editing service, you can request a specific style of English (US or UK).

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, and US English is the least flexible. Bear in mind that the rules are not always very firm: there are many exceptions, and the preferred conventions are constantly changing.