Leant › UK vs US spelling: the common differences
UK vs US spelling: the common differences
Most UK and US spelling differences follow a handful of patterns. Learn the patterns and you will get the vast majority right.
Pattern 1: -our and -or
| UK | US |
|---|---|
| colour | color |
| favour | favor |
| neighbour | neighbor |
| honour | honor |
| humour | humor |
| flavour | flavor |
Exceptions: a few words are the same in both, such as error and horror.
Pattern 2: -re and -er
| UK | US |
|---|---|
| centre | center |
| theatre | theater |
| metre (unit) | meter |
| litre | liter |
| fibre | fiber |
In British English a meter is a measuring device, such as a gas meter, while the unit of length is a metre.
Pattern 3: -ise and -ize
British writing often uses -ise (organise), American writing always uses -ize (organize). See -ise or -ize.
Pattern 4: -ence and -ense
| UK | US |
|---|---|
| defence | defense |
| offence | offense |
| pretence | pretense |
| licence (noun) | license |
| practice (noun) / practise (verb) | practice (both) |
Pattern 5: doubled L
| UK | US |
|---|---|
| travelling | traveling |
| travelled | traveled |
| cancelled | canceled |
| labelled | labeled |
| fulfil | fulfill |
| enrol | enroll |
Pattern 6: -ae and -oe words
British spelling keeps some of these in specialist words (anaesthetic, paediatric), while American usage often drops the a or o (anesthetic, pediatric). In ordinary words the simplified spelling is now common in the UK too, such as encyclopedia.
Why the differences exist
In the early 1800s Noah Webster, an American lexicographer, pushed for simpler spellings in the new country, which is why many American words are shorter. British spelling mostly kept the older forms, many of them borrowed from French. Neither is more correct; they are two conventions that grew apart.
The practical point for writers is that both are standard, and readers are used to seeing each in its own country.
Single words to learn
| UK | US |
|---|---|
| grey | gray |
| tyre | tire |
| kerb | curb |
| cheque (bank) | check |
| programme (TV, event) | program |
| aluminium | aluminum |
| plough | plow |
| mould | mold |
| sceptic | skeptic |
| jewellery | jewelry |
| pyjamas | pajamas |
| cosy | cozy |
Note that program is also the normal British spelling for a computer program.
Past tense words
American English uses -ed for learned, spelled, dreamed, burned and leaned. British English accepts -t as well. See the -t words and leant or leaned.
Which should you follow?
Follow the spelling of your audience. If you write for UK readers (customers, a local council, a school), use the UK column throughout. If you write for readers in the US, use the US column. If your readers are worldwide, either is fine, but be consistent. Mixing colour with organize in the same paragraph looks careless, even if each word is correct somewhere.
How to check a word
- Look it up in a current dictionary; it will mark British and American forms.
- Set your document language to English (UK).
- Search your document for the word and check every instance, not just the first.
Other points
- Dates: British writers put the day first (2 November 2026); Americans often put the month first.
- Towards: more common in British English; toward in American.
- Whilst and amongst: used in British English but sounding formal; while and among work everywhere.
When in doubt, check a current dictionary.