British English (en-GB) is English as written and spoken in the United Kingdom, and en-GB is the standard code that tells browsers, search engines and software that a page is written in it. For a website, it covers two things: the technical settings that declare the language, and the spelling, vocabulary and formats that UK readers expect.
How British English works on a website
The language code appears in a few places. The lang attribute on the page’s opening HTML tag should read “en-GB”, which helps screen readers choose the right pronunciation and lets browsers offer the right spellchecker. The Open Graph tag og:locale uses an underscore, “en_GB”, and tells social platforms which locale the page belongs to. In WordPress, setting Settings > General > Site Language to English (UK) makes the theme output lang="en-GB", and most SEO plugins take og:locale from the same setting. The date format is a separate option on that screen, so check it too.
The writing side is the larger job. British spelling uses -ise in words like optimise and organise, -our in colour, favour and behaviour, -yse in analyse, -re in centre, and doubled consonants in travelled and cancelled. Vocabulary differs too: postcode not zip code, mobile not cell phone, solicitor, estate agent, high street, holiday, trousers, petrol, VAT. Dates are written day first, 4 October 2026 or 04/10/2026, prices carry the pound sign, and phone numbers follow UK formats such as +44 20 7946 0000.
Why it matters
Search engines are generally good at matching spelling variants, so a page with American spellings can still rank in the UK. The bigger effect is on the reader. A UK buyer who meets “zip code”, a date like 10/04/2026 meaning 4 October, or prices in dollars quickly concludes the business is not really based here, or that the copy was lifted from somewhere else. That doubt costs enquiries.
Vocabulary also shapes which searches you match. People in the UK search for “estate agents”, “car insurance quote” and “letting agent fees”, not American equivalents. Writing in the words your customers use is basic keyword relevance, and it is a key part of a consistent tone of voice.
A site that serves only the UK, in one language, does not need hreflang. Hreflang exists to tell search engines which version of a page to show in which country or language when there are several. With one market and one language, the correct lang attribute and good local signals are enough.
Common mistakes
- Leaving the site language on the default English (United States), so the HTML declares en-US while the copy is British.
- Mixed spelling on the same page, often where a theme, plugin or AI writing tool has inserted American forms.
- Adding hreflang tags to a single-market site, which adds complexity and errors with no benefit.
- American date formats in blog posts, events and order emails, which can genuinely mislead customers.
- Forgetting the hidden text: form labels, buttons, error messages and automated emails.
How to act on it
Set the CMS language to English (UK), then view the source of your homepage and check the HTML tag reads lang="en-GB" and og:locale reads “en_GB”. Set your spellchecker and any AI writing tool to British English, and write a short style note for anyone who writes for the site. Then read through forms, checkout and email templates, where American defaults tend to survive. Making copy read naturally to UK customers is part of the content SEO and strategy work I do.