Most British and American business writing is identical. The differences are narrow, repeated and highly visible: a handful of spelling patterns, a few punctuation conventions, the order of a date, and perhaps thirty words that mean different things. That narrowness is the point. You can learn the whole list in an afternoon, and once you have, no reader will ever guess which country you learned to write in.
Everything the converter knows is listed below: the full list of 166 differences, grouped into spelling, word choice and the forms both markets accept.
The harder question is not what the differences are, but which variant you are writing in. That decision belongs to the reader, not to the writer's nationality.
Pick the variant your reader expects
A UK limited company selling to UK procurement teams should write British English even if the founder is American. A solo consultant selling a course to US buyers should write American English even if she is in Bristol. The reader's expectation beats the writer's habit every time, because spelling variants are read as a signal of who the page was made for.
The failure mode is mixing. A homepage that says organise in the headline, program in the pricing table and color in the footer reads as translated or scraped. Buyers rarely comment on it, and they do quietly downgrade the page.
Two rules keep this simple:
- One variant per property. Every page, email template, invoice and error message uses the same variant. Mixed usage inside one site is worse than the wrong variant used consistently.
- Pick by market, then stay put. If you sell into both markets, run two versions of the pages that convert, and one consistent variant everywhere else.
Where the differences actually bite
Six patterns cover most of the spelling. Learn the pattern rather than the word list, and you can handle words you have never seen before.
| Pattern | British | American | Rule of thumb |
|---|---|---|---|
| -our / -or | colour, favour, behaviour, labour | color, favor, behavior, labor | Drops the u in US English, with glamour and a few brand names as exceptions. |
| -ise / -ize | organise, recognise, prioritise | organize, recognize, prioritize | Both endings are accepted in UK English; -ise is the house default here. Never mix within one document. |
| -re / -er | centre, metre, theatre, fibre | center, meter, theater, fiber | Applies to the unit metre; a measuring device is a meter in both. |
| -ce / -se | defence, licence (noun), offence | defense, license, offense | UK English keeps the noun/verb split: licence the noun, license the verb. |
| Doubled consonant | travelling, cancelled, labelled, modelling | traveling, canceled, labeled, modeling | UK doubles the final l before a suffix. |
| One-offs | cheque, programme, grey, tyre, kerb, sceptical, aluminium | check, program, gray, tire, curb, skeptical, aluminum | Memorise these; there is no pattern to lean on. |
If you need to switch a finished draft, the spelling converter handles around 170 pairs including plurals and past tenses. It does not touch terminology, which is the harder half of the job and belongs to a human edit.
Punctuation and typography
Four conventions differ often enough to notice:
- The serial comma. British publishing style omits the comma before and in a list; US style, following the Chicago Manual, requires it. In business writing, use the comma when it removes ambiguity — we interviewed the founders, the finance lead, and the lawyer — and skip it otherwise. That is defensible in both markets.
- Quotation marks. UK English puts logical punctuation inside the marks only when it belongs to the quote; US English puts commas and full stops inside almost always. British style also prefers single quotes for a first-level quotation, which surprises US readers, so double quotes are the safer commercial choice.
- Full stops in abbreviations. UK business writing increasingly writes eg, ie and etc without full stops; US style keeps e.g. and i.e. This is house style, not law — pick one and record it.
- Contractions and directness. Both markets accept we'll and you'll in B2B copy. US business writing is generally more direct about the offer and the ask; UK writing tends to qualify. Neither is more correct, but a UK page that opens with three sentences of context loses US readers, and a US page that opens with a hard claim reads as oversold to UK readers.
Dates, numbers and currency
These cause real errors, because a misread date can cost money.
| Item | UK convention | US convention | What to do |
|---|---|---|---|
| Date | 24 October 2026 or 24/10/2026 | October 24, 2026 or 10/24/2026 | Write the month as a word in anything contractual. Numeric-only dates are ambiguous for the first twelve days of every month. |
| Time | 14:30, or 2.30pm | 2:30 p.m. | Add the time zone in scheduling copy: 14:30 GMT. |
| Thousands | 1,000 or 1 000 | 1,000 | The comma is safe in both. Never use a spaced separator for a US audience. |
| Decimal | 1.5 (point) | 1.5 (point) | Both use a point. Only some EU languages use the comma — do not import it. |
| Currency | £1,200, VAT extra | $1,200, tax extra | State whether tax is included. This is the single most common source of invoice disputes across borders. |
One trap worth naming: billion. Both markets now mean a thousand million, so the old British meaning is dead. Do not use bn in consumer copy where a reader might read it as a different order of magnitude — write 1,000 million only if you enjoy being misunderstood.
Vocabulary that changes meaning
These are not spelling variants. They are different words for the same thing, and using the wrong one makes a sentence sound foreign rather than misspelled.
| Concept | UK | US | Note |
|---|---|---|---|
| Home | flat | apartment | |
| Work history | CV | résumé | Résumé in the US; CV in the UK means the same document, not an academic CV. |
| Address code | postcode | ZIP code | |
| Payment instrument | cheque | check | Also check as in restaurant bill, which is bill in the UK. |
| Phone | mobile | cell phone | |
| Time off | holiday | vacation | Holiday in the US means a public holiday. |
| Accounting period | financial year | fiscal year | |
| Company form | Ltd, plc | Inc, LLC, Corp | Do not translate these. They are legal facts. |
| Tax on sales | VAT | sales tax | Different mechanics, different thresholds, different documentation. |
| Public school | a fee-paying school | a state school | The clearest example of a term that inverts. Avoid entirely. |
Titles, companies and legal names
Use the entity's registered name exactly as filed, including Ltd, plc, Inc or LLC. Do not add a full stop after Ltd — the company register does not use one, and neither should you. Job titles are lower case in running text (the finance director said) and capitalised only in a signature block or a directory listing.
Honorifics matter more in UK correspondence than US: Dear Ms Okafor is safer than Dear Sarah until invited otherwise, and Dear Sir/Madam is now read as a template. In US business email, first names arrive faster and Mr can sound stiff.
What not to localise
Some things should survive the switch untouched:
- Legal terms and statute names. GDPR, VAT, Companies House and HMRC have no US equivalent. Explaining them is fine; renaming them is not.
- Quoted material. If you quote a customer, keep their spelling. Editing a testimonial into your variant makes it look written by you.
- Product and brand names. A product called ColourPro stays ColourPro in the US.
- URLs, file names and code. Changing a slug to match spelling breaks links and analytics history.
- Currency in a contract. Convert and state the rate date, or invoice in the original currency. Do not silently rewrite the figure.
Record the decision
Write down which variant the business uses, which exceptions apply, and who decides when a new term appears. One page is enough, and it stops the same argument every quarter. Our house style guide shows the twenty or so entries that earn their place, and style guide basics covers the format.
Then run the mechanical checks before publishing: the converter for variants, the readability checker for sentence length, and proofreading tips for the rest. If you are briefing someone else to write it, put the variant in the brief — see how to brief a freelance writer.
Checklist before you publish
- The variant matches the market, not the writer.
- No mixed spelling inside the page, and none between the page and its emails.
- Dates written with the month as a word wherever money or deadlines are involved.
- Currency marked, with tax treatment stated.
- Legal entity names untouched, with correct suffixes.
- Terminology checked for the ten vocabulary pairs that change meaning.
- The decision recorded, so the next writer does not reopen it.
None of this makes the writing better. It makes it look like it was written by someone who knows who they are writing for, which is the part readers judge first.
