American English vs UK/Australian English: Spelling Differences Explained

Introduction

English spelling varies across regions, and the differences between American English (AmE) and British/Australian English (BrE/AuE) are among the most noticeable. Many of these variations emerged during the 18th–19th centuries, particularly through spelling reforms promoted by Noah Webster, who aimed to simplify spelling in the United States. British and Australian English generally retained older French- and Latin-influenced forms.

Although many spelling differences follow predictable patterns, not all words adhere to the rules. Some words are exceptions due to their origin, frequency, or historical usage. Understanding both the rules and the exceptions is key to consistent, professional writing.

1. -our vs -or

One of the most recognizable differences is -our in British/Australian English vs -or in American English.

Rule:

• Short, common, native English words → always keep -our in all variants. Examples: our, your, hour, tour, sour, flour, pour

• Longer words, often French-derived nouns/adjectives → AmE drops the “u” → -or, while BrE/AuE retains -our. Examples: colour/color, labor/labour, honour/honor, neighbour/neighbor, favour/favor

Exclusions / Special cases:

• glamour — standard spelling in BrE/AuE and the US; “glamor” exists as a less common American variant.

The difference is etymology-based, not strictly word length. Short words tend to be native and remain unchanged; longer words often came from French and are the ones American English simplified.

2. -re vs -er

Rule:

• French-derived nouns and adjectives ending in -re → American English often changes to -er.
• Exclusions:

  1. Verbs or non-French-derived words → retain -re

     • Examples: derive, adhere, interfere, revere

  2. Words where -er is an affix added to a root (agent nouns like “teacher,” “baker”) → retain -er

Other words unchanged in both variants: acre, ogre, massacre, mediocre.

The -re → -er change applies only to nouns/adjectives borrowed from French, not to verbs or words with derivational -er suffixes.

3. -ize vs -ise

Verbs ending in -ize/-ise differ based on etymology, not just the letter before the suffix.

Rule:

1. Greek/Latin-derived verbs (from -izein or -izare) → AmE prefers -ize, BrE/AuE can use -ise.

   • Examples: organize, authorize, realize, analyze, recognize, specialize

2. French/Old English-derived verbs → always -ise, even in American English.

   • Examples: advertise, exercise, surprise, supervise, revise

Quick reference map:

Differs (-ize in AmE / -ise in BrE/AuE)
    nize → organize, recognize
    lize → realize, specialize
    lyze → analyze
    rize → authorize

Always same (-ise)
    tise → advertise
    cise → exercise
    vise → supervise, advise, revise
    rise → surprise

Note: The spelling is determined by the origin of the word, not the preceding letters.

4. Double Consonants

Rule:

• BrE/AuE often double consonants when adding suffixes (-ed, -ing, -er).

Other words unchanged in both variants: parallel, compelling, propeller.

5. -ce vs -se (Noun / Verb Distinction)

5.1 Noun and verb have different endings (BrE/AuE distinction)

In American English, verbs usually use -se, nouns -ce, simplifying the distinction:

• licence/license → license for both
• practice/practise → practice for both
• advice/advise → same as BrE

5.2 Noun and verb have the same spelling (no change)

6. -ogue vs -og

Why the difference exists:

• Words ending in -ogue come from French, where the suffix indicates “speech, writing, or collection” (-logue).
• American English often drops the “ue”, simplifying spelling while keeping pronunciation largely the same.
• British and Australian English generally retain the original French ending to preserve traditional spelling.

7. Irregular and Historical Spellings

These differences usually reflect historical forms preserved in BrE/AuE or simplifications adopted in AmE. Many must be memorized individually.

Conclusion

Spelling differences between American and British/Australian English are systematic and historically grounded, but not every word follows the rules.

• -our → -or → French-derived words differ; native or short/high-frequency words remain unchanged.
• -ize → -ise → Greek/Latin-derived verbs differ; French/Old English-derived verbs always stay -ise.
• -re → -er → applies only to French-derived nouns/adjectives, excluding verbs and -er suffix agent nouns.
• -ce vs -se → mostly limited to licence/license, practice/practise, advice/advise, with other words keeping the same spelling.
• -ogue → -og → AmE simplifies French endings by dropping the “ue”; BrE/AuE retains the original spelling.
• Double consonants and irregular/historical spellings follow similar historical or etymological patterns.

Understanding these rules and exceptions allows writers to choose a consistent style and communicate professionally in either American or British/Australian English.