Australian dads are being shortchanged, cheated by their own offspring who will spend less than half on Father's Day than they did spoiling mum for Mother's Day.

While Australians splurged an estimated $1.4 billion treating their mums on Mother's Day, they're expected to spend $676.5 million for Father's Day on September 1, according to a study by IBISWorld.

The average adult will spend about $37.30 on their dad this year, the market research company's study said.

IBISWorld senior industry analyst Emily Witham said the heavier emphasis by retailers on Mother's Day was part of the reason for the injustice.

"Mother's Day has been around longer and it's much more heavily advertised," Ms Witham said.

"There's a big emphasis on not only taking mum out for a meal but also getting chocolates, flowers, jewellery, spa visits, pampering gifts.

"The value of the purchases are often much higher than what you'd buy dad - a bottle of whisky or socks and jocks or taking him out for lunch.

"Fathers are more traditionally seen as looking for a break or looking to spend some more time with family, there's a less materialistic view of it and that's supported by the advertising."

This year dads will most likely look forward to a meal with the family or a gift card as Australians remain cautious about how they spend their money, Ms Witham said.

She said weak consumer confidence has seen Australians dining out less, and leaving meals out at restaurants for special occasions like Father's Day.

IBISWorld general manager Karen Dobie said the popularity of do-it-yourself renovation shows had seen a boom in hardware and electrical goods spending, which is expected to be the second most popular area of spending this Father's Day, after eating out.