Shoppers across Australia are predicted to splash nearly $2.1 billion on Boxing Day alone, offsetting a shaky year for retailers, struggling with subdued consumer confidence and soft sales in the lead-up to Christmas.

Between Friday and mid-January, consumers are expected to pour $16.1 billion into shop tills at the sales, an increase of 3.6 per cent on last year's figure, the executive director of the Australian Retailers Association,  Russell Zimmerman said.

Dozens of early birds shoppers will queue outside David Jones Sydney CBD store before the sun's first rays hit the pavement, seeking pole position and a $50 gift card from the retail giant.

Model Jesinta Campbell will ring the opening bell at 5am before hundreds of people, signalling the start of the national spending binge.

Across the street, Myer will also be opening its doors at 5am to what chief executive Bernie Brookes has billed as "the biggest stocktake sale that we've had."

Only NSW Myer stores in Bondi, Shellharbour, Erina and Albury will open at the lazier 7am. The rest will be shut.

The retailer is bracing for a million customers nationally to stampede through its doors on Boxing Day - or 100,000 every hour - and 17 million over the stocktake sale period, which ends January 26.

It is expecting 48,000 dresses, half a million intimate apparel and hosiery and 80,000 shoes in the women's department to fly out the doors in the first week.

About 200,000 men's business shirts and 55,000 sheet sets at vastly reduced prices will be sold, Myer said.

Anna McPhee, chief executive of the Australian National Retailers Association, said the average family will fork out $273 at Boxing Day sales.

Pre-christmas discounting and early online boxing day sales will not dent the shopping frenzy, she said.

"The boost to household budgets from record low interest rates and lower fuel prices will go towards making this year's Boxing Day and end of year sale period better than last year."

The ANRA forecasts $627 million to be spent on Friday in NSW, $33 million less than in Victoria where trading is unrestricted.

Ms McPhee blasted the state and federal government for not allowing more than 70 council areas in NSW to freely trade on Boxing Day, curbing the state's retail activity.

But retailers are already enjoying post-Christmas sales profits, with electronics chains Dick Smith and JB Hi-Fi jumping the gun and launching their online clearance sales early.

Dick Smith began its Boxing Day hoohah at 4pm on Christmas Eve. Its anticipating roaring sales for audio devices. Wearable fitness products sales are expected to grow five-fold.

"Customers are more sophisticated than ever before and are prepared to put in the work to find the best priced product," said chief executive Nick Abboud. "That's why we've upped the game."

Fair Trading Minister Matthew Mason-Cox urged shoppers to stick to a budget, research about prices and shop online only using reputable sellers and websites.

So far this year, the consumer watchdog has been hit with 5607 refund-related complaints - already exceeding last year's total figure of 5196.

"A retailer is not required by law to offer a refund or exchange purely because the consumer simply changes their mind and no longer wants their purchase," he said.

"However, a refund, repair or replacement must be offered if goods are faulty or defective, different to the sample shown or described in advertising, or not fit for the purpose intended."

BIG NUMBERS

• $2.1 billion to be spent at Boxing Day sales nationally
• $627.3 million to be spent at Boxing Day sales in NSW
• $273 to be spent by the average family on Boxing Day
• $16.1 billion to be spent at sales from now until mid-January
• 1.2 million retail workers in Australia
• 50 business shirts sold a minute at Myer