Personalized vs. Personalised: The Story of a Single Letter

Language is a living, breathing thing, constantly shifting across borders, oceans, and cultures. Yet, few things spark quite as much low-stakes debate among writers, editors, and students as a single stray letter. Case in point: personalized versus personalised.

At first glance, it looks like a simple typo. But underneath that single letter swap lies a fascinating look at how English evolved into a global language with distinct regional flavors.

The Short Answer

Before diving into the details, here is the rule of thumb you need:

• Personalized (with a z) is the standard spelling in American English (US) and is widely accepted globally, including in international tech and business contexts.
• Personalised (with an s) is the standard spelling in British English (UK), as well as in Australian, Canadian, New Zealand, and South African English.

Both spellings are 100% correct. The only “wrong” move is mixing them haphazardly within the same piece of writing!

Why the Difference Exists: The -ise vs. -ize Divide

To understand why these two words look different, we have to look back at the history of English spelling.