Writing UK and US English

See also: Writing Effective Emails

The English-speaking countries of the world may on the face of it seem to share a common language. However, just as accents vary in different countries, the way that language is used can also vary widely from place to place. Words may also have very different meanings in Australia, the US, and the UK. Add Canada, New Zealand, and South Africa into the mix, and it will be clear that there is considerable potential for confusion.

This page focuses mainly on the differences between written English in the US and UK. It also briefly touches on some of the main differences in terminology. It is worth being aware, however, that other variants of English are also recognised.

Different Words, Different Meanings

US and UK English has not been the same language since the 16th century, and in that time, a number of differences have crept in. The same word may have developed different meanings, and there are also a number of cases where the two use completely different terms for the same thing.

A few examples are given in the table below.

US English UK English
Sidewalk Pavement
Realtor Estate agent
Pants Trousers
Underpants Pants
Chips Crisps
Fries Chips

The last four lines also show that there are a number of cases where the same word has somewhat different meanings in the US and UK.


If you are not a native English speaker, or you need to produce a document in the ‘other’ form of English, it is worth getting someone who is familiar with the ‘right’ form of English to check it for you and make sure you have not used the wrong word anywhere.

Spelling in UK and US English

There are a number of broad general differences between US and UK English spelling. They are set out in the table below. Generally, US English is simpler and more phonetic (that is, it looks more as it sounds).

Rule US English UK English
Verbs ending -ise/-ize, such as realise/realize. Usually take the -ize, -ization and –izing ending. Both –ise and –ize are accepted, although –ise is more common.
Note: There are a number of exceptions to this rule (for example, only analyse is correct, not analyze). If in doubt, it is probably better to use the –ise spelling.
Nouns ending -er/-re, such as centre/center Usually take the -er ending
When the noun becomes a verb, -ing is added (e.g. centering)
Usually take the -re ending
When the noun becomes a verb, the –e is dropped before adding –ing (centring).
It does not follow that all US words ending –er take the –re form in British English. Exceptions include filter and cover.
Nouns ending –ence or –ense, such as defence/defense, offence/offense Usually take the –ense ending Usually take the –ence ending
Words ending –or or –our such as behaviour/behavior, favour/favor -or ending -our ending
Words from Greek with double vowels –ae and –oe such as leukaemia/leukemia, and estrogen/oestrogen. Usually drop the –a or –o in favour of –e alone
Note: There are exceptions to this rule. Archaeology, for example, is acceptable in US English, as is caesarean (although cesarean is also used).
Tend to retain both vowels to maintain the link to Greek
The past forms of verbs ending in a vowel plus –l, such as travel and grovel. The past participle (e.g. traveled) is formed by adding –ed and the present participle (e.g. traveling) by adding –ing.
There is no second –l added.
The past participle is formed by adding –led (e.g. travelled) and the present participle (e.g. travelling) by adding –ling.
A second –l is therefore added before the suffix.
Verbs ending il/ill such as instil/instill, or fulfil/fulfill Use the -ll ending Use the –l ending
Adjectives ending –ful formed from a noun ending with –ll, such as skill and skilful/skillful Add –ful to the noun e.g. skillful Drop one –l from the noun, before adding –ful.

One other common variant that is worth mentioning is practice/practise.

  • In the US, the only form used is practice. This is both noun (“I have done my practice today”) and verb (“I practiced my violin today”).
  • In the UK, practise is the verb, and practice the noun (“I have done my practice” vs. “I practised my violin”).

Oxford or standard UK English?

Oxford English uses the Oxford English Dictionary as the standard reference. The main difference between Oxford and standard UK English is that Oxford English uses –ize spellings for a number of verbs that could be either –ise or –ize in standard English. The reason for this is that the –ize suffix is considered to be closer to the original Greek root.

Oxford English is used by the Oxford University Press, and a number of other British journals and publishers. It is also used by the United Nations and its agencies.

Which form of English you use, and are most familiar with, will depend where you learned your English. If you learned in the US, you will probably be most familiar with US spelling. If you learned in the UK, or somewhere like India or Australia, where UK English has a historically stronger influence, you will probably have learned UK English.

Generally, it is likely to be acceptable to use either US or UK English, but not a mixture.

Skills You Need is a British website and we use UK English in our articles and eBooks. Our guest posts are written by authors from all over the world and may use US or other international English.


When writing in a word processing package, set the spell-checker to the language in which you are writing, and switch it on. This will automatically flag up any words that you have inadvertently spelled the wrong way.


In Word, the UK English option will allow either –ise or –ize spellings for many words. It is good practice to use one or the other, so you will need to use the ‘search’ function to check that you have not used a mixture of the two. Remember to check for –iz(s)ation and –iz(s)ing as well as –iz(s)e.

For Oxford English, use the UK English option, and search and replace –ise,  –isation and –ising.

Not as bad as it sounds!

It may sound like managing US or UK spelling is challenging, but it is not as bad as it sounds. Most word processing packages can spell-check in either US or UK English, as well as a number of variants, including Australian English. As long as you set the options correctly before you start, you should not have any problems.