The world's biggest retailer is primed for a shopping bonanza as cash-strapped customers increasingly wait for major sales events to pounce on bargains.

Amazon on Tuesday kicked off its seven-day Prime Day sale, one of its three big events of the year.

The e-commerce giant has hired hundreds of seasonal workers for the event, which features discounts on items ranging from electronics to fashion to books and toys.

Such events may be becoming a budgeting tool for cash-strapped households, with the average Aussie expected to spend $425 on mid-year sales in 2026, according to research commissioned by Amazon.

"We know 80 per cent of Australians are now waiting for sales events to make their purchases and that's a very interesting shift," Amazon Australia general manager Sherif Zaki said.

Despite the cost-of-living crunch, the online retailer has seen a trend towards what the industry calls "premiumisation", in which shoppers are willing to pay more for quality items.

"Customers aren't just looking for the cheapest option, they're looking to save on everyday essentials and invest in quality where it matters," Mr Zaki said.

Amazon Australia has been preparing for the Prime Dale sale for months, stocking up on inventory at its 20 warehouses around the country.

AAP visited two on Monday, BWU2 and BWU6, located a few minutes' drive from each other in the western Sydney suburbs of Kemps Creek and Horsley Park.

Like all of Amazon's warehouses around the globe, they're named after the three-letter code of the nearest airport, in this case Bankstown.

BWU2 is the biggest customer fulfilment centre in the southern hemisphere.

It houses about 20 million units of inventory across 200,000 square metres, about the land area of Taronga Zoo or 24 rugby union fields.

The warehouse is unique because it's the country's only robotic fulfilment centre, Mr Zaki said, although Amazon is building two more, one north of Melbourne and another south of Brisbane.

"The robots handle all the heavy lifting, all the repetitive movement, anything that's ergonomically demanding, so that our team members can focus on the work that requires human judgement and coordination," he said.

More than 3000 employees work at BWU2.

Amazon Australia also expects that many of the 850 seasonal workers it has hired will go on to become part of its permanent workforce of over 8000.

Daniel Bannister, 24, has been working at Amazon since 2022 as a dock clerk and said the sale period was always a busy time for his team.

"It's definitely a challenge, but it brings everyone together," he said.