Personalised vs Personalized: What is the Difference?

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Personalised vs. Personalized: What is the Difference?

When you are typing out an email, working on a school assignment, or designing a custom gift, you might notice a little red squiggly line appear under words like personalised or behavior. Depending on where you live—or which settings your computer is using—you might find yourself wondering: Is it spelled with an s or a z?

The short answer is simple: Both are correct.

The difference isn’t about right or wrong; it is all about geography. Let’s dive into why this spelling split exists and how to know which one you should use.

The Core Difference: Geography, Not Grammar

At its heart, the difference between personalised and personalized comes down to regional variations in the English language:

Personalised (with an ‘s’): This is the standard spelling in British English, which is used in the United Kingdom, Australia, New Zealand, South Africa, Ireland, and many other Commonwealth nations.
Personalized (with a ‘z’): This is the standard spelling in American English, which is widely used in the United States and heavily influences international software and digital platforms.

Both words mean the exact same thing: adapting a product, service, or message to suit an individual person’s specific needs, preferences, or name (like engraving your initials onto a water bottle).

Where Does the “Z” Come From?

Many people assume that American English changed the spelling just to be different, but the history goes back centuries.

The letter z represents a phonetic sound used in Greek and Latin roots (derived from the suffix -izere or -izare).

Noah Webster, the creator of the first major American dictionary in the early 19th century, championed simpler, more phonetic spellings. He preferred the -ize ending because it reflected how the word actually sounds when spoken aloud.
Meanwhile, British English (and publishers like the Oxford English Dictionary) often kept the traditional British preference for the -ise ending, which was heavily influenced by French spelling conventions.

Interestingly, even in the UK, many dictionaries and style guides (including the Oxford English Dictionary) historically listed both spellings, though -ise became the dominant national standard for British publishers.

Quick Guide: Which One Should You Use?

Choosing the right spelling is usually a matter of matching your audience or your publication’s style guide:

Use personalized (with a ‘z’) if: You are writing for an American audience, publishing on an American platform, or following a style guide that requires American English (like AP Style). Many global tech companies and software default to this spelling.
Use personalised (with an ‘s’) if: You live in the UK, Australia, or another Commonwealth country, or if you are submitting work to a school or organization that specifically requests British English.

Top Tip: Whichever spelling you choose, consistency is key! Try not to mix personalized and optimised in the same piece of writing. Pick one regional standard and stick with it from start to finish.

Summary Table

Ultimately, whether you use an s or a z, your readers will know exactly what you mean!

Personalised vs Personalized: What is the Difference?