Personalised vs. Personalized: What’s the Difference?

Personalized vs. Personalised: The Spelling Split That Divides the English-Speaking World

Language is a living, breathing thing, constantly evolving and shifting across borders. Few linguistic quirks highlight this better than the humble letter “S” versus the “Z.”

Whether you are crafting a marketing campaign, writing an academic paper, or setting up a global software platform, you have likely stared at the words “personalized” and “personalised” and wondered: Did I just make a typo, or am I accidentally writing in a different dialect?

The short answer is neither is wrong. Both are correct spellings of the exact same word; the only difference is the geography of your audience.

The Root of the Difference: Z vs. S

To understand why this split exists, we have to look across the Atlantic Ocean.

• Personalized (with a “Z”): This is the standard spelling in American English (US). It is also widely used in Canadian and international business contexts influenced by American media and technology.
• Personalised (with an “S”): This is the standard spelling in British English (UK), as well as in Australia, New Zealand, South Africa, Ireland, and many other nations that follow British spelling conventions (often referred to as Commonwealth or Oxford spelling).

Both versions stem from the verb personalise (or personalize), derived from the root word person.

Why Does This Happen? (A Quick Etymology Lesson)

Many people assume that American English changed the spelling just to be different, but the history is a bit more nuanced.

The use of “-ize” actually dates back to Greek roots (ending in -izein). In the 16th and 17th centuries, British English commonly used both “-ize” and “-ise.” However, during the 19th century, British lexicographers—most notably the creators of the Oxford English Dictionary (OED)—favored the spelling “-ise” for words derived from French.