Grammar Check guide

British vs American spelling: the differences and the rules

American spelling usually drops or simplifies letters that British spelling keeps: color and colour, center and centre, traveling and travelling, defense and defence. For -ize and -ise, American English uses -ize, while British English accepts both. Canadian English mixes the two, Australian and Indian English follow British spelling, and whichever you choose, the rule that matters most is to use it consistently.

Updated 12 November 2026 · 8 min read

The main patterns

Most differences follow a handful of patterns. Learn these and you can spell thousands of words either way.

British and American spelling patterns
Pattern	British	American	Watch out for
-our / -or	colour, favourite, behaviour, neighbour	color, favorite, behavior, neighbor	Glamour keeps its u in American English too.
-re / -er	centre, metre, litre, fibre, theatre	center, meter, liter, fiber, theater	A meter that measures (a gas meter) is -er in British English too.
-ise / -ize	organise or organize, realise or realize	organize, realize	Some words are -ise everywhere: advertise, compromise, exercise, surprise, supervise.
-yse / -yze	analyse, paralyse	analyze, paralyze	Unlike -ise, British English keeps -yse.
Doubled L	travelling, cancelled, modelling, labelled	traveling, canceled, modeling, labeled	It works the other way in enrol/enroll, fulfil/fulfill and skilful/skillful.
-ce / -se	defence, offence, licence (noun)	defense, offense, license	British English uses license for the verb.
-ogue / -og	catalogue, dialogue, analogue	catalog (often), dialogue, analog	Dialog is a box on a computer screen in both.
ae, oe / e	paediatric, encyclopaedia, manoeuvre	pediatric, encyclopedia, maneuver	Many British writers now use encyclopedia too.
Dropped e	judgement, ageing	judgment, aging	Judgment is standard in British legal writing.

Is -ize wrong in British English?

No. British English has always allowed both. The -ize form, known as Oxford spelling, is used by some British publishers and by many international organisations, because it follows the word’s Greek root (-izein). The -ise form is more common in British newspapers and everyday writing, and it is what most British readers expect.

Two things are worth knowing:

-yse never becomes -yze in British spelling. Analyse and paralyse keep their s even in Oxford spelling.
Some words are -ise in every variety. Advertise, advise, compromise, despise, exercise, revise, supervise, surprise and televise are never spelt with z, because the ending isn’t the -ize suffix.

Grammar Check’s British setting accepts both organise and organize, so it won’t push you either way: choose by your organisation’s style, or by habit, and keep to it.

Practice or practise, licence or license

British English spells a few nouns with -ce and the matching verbs with -se. American English uses one spelling for both.

Noun and verb pairs
	British noun	British verb	American (both)
practice	She went to football practice.	She needs to practise more.	practice
licence	a driving licence	licensed to sell alcohol	license

A trick for British English: advice (noun) and advise (verb) follow the same pattern, and you can hear the difference. If advice would fit, use the -ce spelling; if advise would fit, use -se.

A checker can’t always help herePractice and practise are both real British words, so a spell checker accepts either one wherever it appears. Only you can tell whether you meant the noun or the verb. In American English, “practise” is a misspelling, and Grammar Check’s American setting underlines it.

Different words, not just different spellings

Some pairs are separate words with their own histories, so no spelling rule will get you from one to the other.

Words that differ between British and American English
British	American	Notes
tyre	tire	Tire (to get tired) is the same everywhere.
kerb	curb	To curb (to hold back) is curb everywhere.
cheque	check	A bill in a restaurant is a check in American English too.
programme	program	A computer program is program in British English too.
aluminium	aluminum	Also said differently: al-yoo-MIN-ee-um and a-LOO-min-um.
aeroplane	airplane	Plane works everywhere.
grey	gray	Greyhound is spelt with an e in both.
plough	plow
pyjamas	pajamas
sceptical	skeptical
storey (of a building)	story	A story you tell is story in both.
jewellery	jewelry

Canadian, Australian and Indian English

Canadian English is a mix. It keeps British colour, centre, travelling, defence and cheque, but uses American -ize and -yze (realize, analyze), and American words such as tire, curb, program, aluminum and airplane.
Australian English follows British spelling, with -ise far more common than -ize. One famous exception is a proper name: the Australian Labor Party spells Labor without a u.
Indian English follows British spelling in most published writing: colour, centre, programme, cheque.
Irish and New Zealand English also follow British spelling.

Names keep their own spelling whichever English you write in: the World Health Organization, Pearl Harbor, the Sydney Harbour Bridge.

What each setting in Grammar Check accepts

Grammar Check has five kinds of English: American, British, Australian, Canadian and Indian. A word that’s right in one and wrong in another is underlined in red with the other spelling as the fix. We ran these words through each setting:

Accepted or underlined, by setting
Word	American	British	Australian	Canadian	Indian
colour	Underlined	Accepted	Accepted	Accepted	Accepted
color	Accepted	Underlined	Underlined	Underlined	Underlined
centre	Underlined	Accepted	Accepted	Accepted	Accepted
center	Accepted	Underlined	Underlined	Underlined	Underlined
grey	Underlined	Accepted	Accepted	Accepted	Accepted
gray	Accepted	Underlined	Underlined	Underlined	Underlined
travelling	Underlined	Accepted	Accepted	Accepted	Accepted
traveling	Accepted	Underlined	Underlined	Underlined	Underlined
defence	Underlined	Accepted	Accepted	Accepted	Accepted
defense	Accepted	Underlined	Underlined	Underlined	Underlined
realise	Underlined	Accepted	Accepted	Underlined	Accepted
realize	Accepted	Accepted	Accepted	Accepted	Accepted
analyse	Underlined	Accepted	Accepted	Underlined	Accepted
sceptical	Underlined	Accepted	Accepted	Underlined	Accepted
skeptical	Accepted	Underlined	Underlined	Underlined	Underlined
tyre	Underlined	Accepted	Accepted	Underlined	Accepted
programme	Underlined	Accepted	Accepted	Underlined	Accepted
aluminium	Underlined	Accepted	Accepted	Underlined	Accepted
aluminum	Accepted	Underlined	Underlined	Accepted	Underlined
cheque	Underlined	Accepted	Accepted	Accepted	Accepted
judgement	Underlined	Accepted	Accepted	Underlined	Accepted

Two things stand out. The British, Australian and Indian settings accept realize as well as realise, because -ize is correct British spelling; and the Canadian setting behaves as Canadian writers do, with British -our and -re but American -ize.

Open Settings. In Grammar Check, tap the gear, then Dialect under English.
Pick your English. On first use it guesses from your browser’s language (en-GB, for example, gives British), so check it once.
Paste your writing. Words spelt the other way are underlined with the fix in one tap. Your text is checked on your device and never uploaded.

Which spelling should you use?

Write for your reader. A UK customer, a UK exam or a UK employer expects British spelling; an American one expects American.
Follow the house style. Many companies, universities and publishers choose one. Some British organisations use -ize on purpose.
Be consistent. Mixing colour and center in one document looks careless in either variety. That is the real mistake readers notice.
Keep quotations and names as they are. Don’t “correct” the spelling in a quote or an organisation’s name.

For the grammar slips that look the same in every English, see our list of common grammar mistakes.

Questions

Is it grey or gray?

Grey is the British spelling and gray is the American one. Both mean the same colour. Canadian, Australian and Indian English use grey.

Is -ize wrong in British English?

No. British English accepts both -ise and -ize; -ize is called Oxford spelling. The -ise form is more common in everyday British writing. Words ending in -yse, such as analyse, keep the s in British English either way.

Is it practice or practise?

In British English, practice is the noun and practise is the verb: you go to practice, and you practise the piano. American English uses practice for both.

Does Canada use British or American spelling?

Both. Canadian English keeps British spellings such as colour, centre and cheque, but uses American -ize endings (realize) and American words such as tire, program and aluminum.

How do I make a spell checker use British English?

Choose British English in the checker’s language setting. In Grammar Check, tap Settings, then Dialect, and pick British, Australian, Canadian, Indian or American English. It checks your writing on your device, free.