It analysed the prices of 222 products across three major supermarket chains online between September last year and July, and found that some products cost even more during bulk-buy promotions.
For instance, for a bottle of 410mL steamed fish soy sauce that has a regular price of HK$13, it cost HK10.95 on average in a buy-one-get-one-free offer. That represented a discount of about 16 percent, far below than consumer expectations of 50 percent off, according to the watchdog.
The council said buyers might assume that larger pack sizes carry better value for money, but that it’s not always the case.
It found the unit price for some items could cost up to 35 percent more for bigger packs compared with smaller ones.
The council’s chief executive Alaina Shum said supermarkets should increase transparency so consumers could make informed decisions, and they could follow the practice of overseas online stores including the UK and Australia that have already made unit prices available.
“Although we don’t have a mandatory requirement here in Hong Kong, they could adopt the display of the unit price, both online as well as in shops, physically, to allow the consumers to make an informed decision without having the need for the customers to calculate the unit price themselves,” she said.
The watchdog said consumers should always look beyond the sale prices and discounts on offer – they should also calculate the unit price and compare the cost with and without the promotion discounts.
On top of an existing website, the council launched a dedicated mobile app last month to better assist buyers with price comparison.
It features prices of about 2,800 products from nine online supermarkets, personal care stores, cosmetics retailers and pharmacies, allowing users to track prices and look for items with significant price reductions, among other things.
“Our intention is to facilitate the users to be able to deduce the unit price more easily and more quickly,” Shum said.
“Launching the new app will allow consumers at any time in a very efficient way to be able to obtain the unit price.”