An analysis of 8.3 billion Westpac customer credit card and debit card transactions has found more than 150,000 retail customers in March paid for at least one AI subscription a month, with an average monthly spend of $37.
That's a nearly 14-fold increase from the 11,000 Australians that paid to use AI in March 2023, and a 145 per cent jump from those paying to use it a year ago.
There was a rapid growth in the use of AI, Westpac's chief AI officer Dan Jermyn said.
"Year-on-year, the pick-up is accelerating, not just progressing at the same rate,'' he said.
"So I think we're really just at the start of this."
Westpac has about 10 million customers in its retail businesses, including its St.George, BankSA and Bank of Melbourne brands.
Their $5.6 million AI monthly spend is just a fraction of Westpac customer's $6.7 billion annual outplay on subscriptions, but Mr Jermyn compared it to streaming services.
Not too long ago such services didn't exist, with Netflix launching in Australia in 2015, but now it and similar services are household staples.
"I think you're going to see AI tools becoming a mainstream utility like that, not just a niche extra," Mr Jermyn said.
Westpac's figures identified spending on AI services such as ChatGPT, Claude and Perplexity, but didn't include Google's Gemini, where access to the chatbot's premium service is included as part of a larger package of tools.
 Many more Australians would be using free AI services, Mr Jermyn said.
The large increase in subscribers has likely been triggered by services like Claude Code and OpenAI Codex, AI-powered coding assistants for software engineers, Mr Jermyn said.
Westpac customer interest in AI has been mirrored by the bank internally.
In February, Westpac rolled out Microsoft 365 Copilot service to its customers, becoming the first large organisation in the region to do so.
"We now have more than 35,000 users of that, and the uptake has been incredible," Mr Jermyn said.
Westpac employees are using AI in their jobs to automate tasks, giving them more time to spend with customers and use their creativity, he said.
When it comes to product development, AI software tools enable Westpac engineers to very quickly create prototypes of new product designs and features, he said.
"It's really empowering our people to serve customers in a way that goes beyond what what was possible before we gave them access to some of this tooling."