Personalised vs. Personalized: Which Spelling Should You Use?

Language is a living, breathing ecosystem, constantly shaped by geography, culture, and convenience. One of the most common battlegrounds for this linguistic evolution is the spelling of words ending in -ise versus -ize. At the center of this friendly cross-Atlantic rivalry are two identical-sounding spellings of the exact same word: personalised and personalized.

Whether you are crafting a marketing campaign, drafting a software product description, or writing an academic essay, choosing the right spelling matters. Let us dive into the differences, the rules, and how to choose the right one for your audience.

The Core Difference: Geography, Not Grammar

The distinction between personalised and personalized is not a matter of correct versus incorrect. Both are fully valid, dictionary-approved spellings. The sole dividing line is regional preference:

• Personalised (with an s) is the standard spelling in British English (BrE) and is widely used across the United Kingdom, Australia, New Zealand, South Africa, Ireland, India, and other Commonwealth nations.
• Personalized (with a z) is the standard spelling in American English (AmE) and is widely adopted in international tech platforms, global software, and increasingly across digital media.

Where Do These Spellings Come From?

To understand why this split exists, we have to look back at the history of English orthography.

The suffix -ize (derived from the Greek -izein and Latin -izare) was historically spelled with a z in English. However, in the 19th century, French spelling conventions heavily influenced British publishing. French preferred the soft -ise ending for many of these words.

While Noah Webster—the father of American lexicography—pioneered a simplified, phonetic approach for American English in the early 1800s (championing the z spelling to reflect pronunciation and etymological roots), British English largely retained the French-influenced -ise spelling, which was later codified by the Oxford English Dictionary (OED).