Spelling Systems Cheat-Sheet

When a word looks "wrong", it is usually not a mistake — it is just the other side of the Atlantic. Almost every British–American spelling difference fits one of six patterns. This is the spot-the-pattern card: glance down it, find the shape your word matches, and you will know instantly which variety it belongs to. For the full explanation of each, the walkthrough is in Spelling Systems: UK vs US at a Glance.

How to use it

1. Spot the ending. Does the word end in one of the six shapes above? If so, it is one of these splits, and the "wrong" version is simply the other country's spelling — not a typo.
2. Match your variety. In a British school, use the left-hand column and set your spellchecker to UK English. Writing for an American reader? Use the right-hand column, and switch the whole piece, not word by word.
3. If it fits none of the six — check the odd one-offs (tyre/tire, grey/gray, pyjamas/pajamas), and if it is not one of those either, it is probably a genuine typo worth fixing.

The one rule that matters most is consistency: pick a side for a piece of writing and keep to it the whole way through. A reader notices the mixing, not the choice. For the most common split of all, see Colour or Color?; for the trickiest, Organise or Organize?.

Watch out: false friends

A few pairs look like spelling splits but are actually different words with different meanings — do not "correct" them:

• practice (noun) vs practise (verb) in British English — both spellings are right, for different jobs.
• program (a computer program, both varieties) vs programme (a TV or event programme, UK only).

When in doubt, check the meaning before you change the spelling.

A memory hook, and one honest exception

Here is a shortcut: the American forms are almost all shorter — color loses a u, center swaps -re for -er, catalog drops the -ue, traveling loses an l. Remember "American English trims the extra letters" and you can usually guess the US spelling from the British one without looking it up.

The one honest exception is -ise/-ize: some careful British publishers (and the Oxford dictionaries) actually prefer -ize — so a British book using organize is not a mistake, just a different house style. If your school says -ise, use -ise; just do not be surprised to see -ize in print.

Where next

• Spelling — the young-learner hub — the bigger map this sits inside
• Spelling Systems: UK vs US at a Glance — the same splits, explained
• Colour or Color? — the most common split, in full
• Organise or Organize? — the -ise/-ize family