American vs British English Spelling: Key Differences Explained

Key takeaways

• American and British English follow different spelling conventions for dozens of common word patterns.
• The most common differences involve the suffixes -our/-or, -re/-er, -ise/-ize, -ence/-ense, and doubled consonants.
• Neither spelling system is wrong, but mixing both in the same document looks careless and undermines professional credibility.
• Consistency matters more than which variety you choose: pick one and stick to it throughout any piece of writing.
• An English tutor can help you identify which variety fits your context and catch inconsistencies in your writing before they reach a reader.

Many learners assume they know English spelling well enough after years of study, until they submit a UK university application written in American spelling, or send a cover letter to a US employer using British conventions. The differences are subtle enough that spell-checkers sometimes miss them, and visible enough to native readers that inconsistency immediately draws attention.

italki operates across 150+ languages with more than 30,000 tutors, giving you access to English tutors who understand both varieties fluently. This guide covers the key British vs American spelling differences organized by pattern, with word lists so you can build a working awareness of each rule and apply it consistently.

Pattern 1: -our vs -or

British English keeps the -our ending from French and Latin origins. American English simplifies to -or. Learn which context calls for which form and practice writing in your chosen variety consistently.

British spelling	American spelling
colour	color
honour	honor
favour	favor
behaviour	behavior
neighbour	neighbor
humour	humor
flavour	flavor
labour	labor
harbour	harbor
glamour	glamour (same, exception)

Study this pattern systematically with an English language tutor who helps you pick one variety and stick to it.

Pattern 2: -re vs -er

British English often keeps the -re ending from words with French origin. American English reverses the letters to -er. Once you choose your variety, apply this rule to all relevant words.

British spelling	American spelling
centre	center
theatre	theater
fibre	fiber
litre	liter
metre	meter
calibre	caliber
sabre	saber
sombre	somber
spectre	specter

Practice reading and writing this pattern in context with an English tutor online.

Pattern 3: -ise vs -ize

American English consistently uses -ize. British English allows both -ise and -ize, with -ise more common in everyday writing. Consistency matters: choose one and apply it throughout your document.

British spelling (-ise more common)	American spelling
organise	organize
realise	realize
recognise	recognize
specialise	specialize
apologise	apologize
criticise	criticize
emphasise	emphasize
minimise	minimize
authorise	authorize

Note: Some words end in -ise in both varieties because the ending is part of the root: “surprise,” “advertise,” “devise,” “exercise,” “supervise.” These are not subject to the -ise/-ize variation.

Drill this pattern consistently with an English teacher on italki to avoid mixing variants.

Pattern 4: -ence vs -ense

British English uses -ence for some words that American English spells with -ense. Keep your chosen variety consistent across your writing.

British spelling	American spelling
defence	defense
offence	offense
licence (noun)	license (noun)
pretence	pretense

Note: In British English, “licence” is the noun and “license” is the verb. In American English, “license” serves as both noun and verb.

Practice noun-verb distinctions in this pattern with online English tutors on italki.

Pattern 5: Doubled consonants before suffixes

British English often doubles a consonant before a suffix like -ed, -ing, -er when the preceding vowel is unstressed. American English usually does not double. Choose one system and maintain it.

British spelling	American spelling
travelling	traveling
cancelled	canceled
modelling	modeling
labelling	labeling
marvelled	marveled
counselling	counseling
signalling	signaling

Master this pattern by writing short paragraphs using words from this table, then review them with an English teacher online.

Pattern 6: -ogue vs -og

British spelling	American spelling
catalogue	catalog
dialogue	dialog
analogue	analog

Other miscellaneous differences

British spelling	American spelling
mum	mom
tyre (car tyre)	tire
grey	gray
cheque	check (payment)
pyjamas	pajamas
kerb	curb
plough	plow
judgement	judgment
ageing	aging
draught	draft

These words fall outside the major patterns, so learning them individually is most efficient. Flashcard review works well for miscellaneous pairs.

Staying consistent: practical tips

The most important rule is not which variety you use but that you pick one and apply it throughout. A document that mixes “colour” and “organization” signals that the writer is not in full command of the language.

Tips for consistency: set your spell-checker to the correct regional English before you start writing. Keep a personal list of the words you most commonly mix up. For professional documents, check the house style of the organization you are writing for, UK universities, UK companies, and American employers often have explicit preferences. Once you know the expectation, build a custom dictionary in your word processor to catch inconsistencies.

Read widely in your chosen variety so the patterns become automatic. British newspapers, American textbooks, and fiction from each region all reinforce these conventions naturally. Over time, your visual recognition will catch inconsistencies before your conscious mind does.

Get real-time feedback on your spelling consistency by writing with an English tutor and reviewing your work together.

Quick reference: which variety for which purpose?

Purpose	Choose
UK university or employer	British English
US university or employer	American English
International business	American English (more widely recognized)
Academic publishing in the UK	British English
Unsure of reader’s expectation	Ask or check the organization’s style guide

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FAQ

Can I mix both varieties?

No. Professional writing expects consistency, and explanation does not make mixing acceptable. Choose one and maintain it throughout. If you are writing for an international audience with mixed expectations, American English is the safer default because it is more widely recognized globally.

Which variety is easier to learn?

American English is simpler in most cases because it has fewer special cases (fewer doubled consonants, consistent -ize endings). However, if you learned British English first, switching creates more cognitive load than just continuing with what you know. Stick with whichever you started with unless your professional context demands the other.

Does the IELTS test prefer British spelling?

Yes. The IELTS exam expects British spelling. The TOEFL and Duolingo English Test expect American spelling. Check the requirements of your specific exam and set your spell-checker accordingly. Using consistent American spelling on the IELTS or consistent British spelling on the TOEFL will reduce your score, even if your writing is otherwise excellent.

Will native speakers judge me for using the “wrong” variety?

Yes, some will. Professional contexts often have strong preferences. University admissions, legal documents, and business communications all notice. That said, native speakers recognize effort and understand that learners may not have controlled both varieties equally. Focus on consistency first, then worry about which variety matches your specific audience.