Online buy-one-get-one-free promotions from supermarkets do not necessarily mean cheaper prices or nearly 50 percent discounts for shoppers, Hong Kong’s Consumer Council said on Monday.  

The council said in a statement that its survey of online prices of 222 products sold by three major supermarket chains showed that for some products, the actual discount “could be as low as 0 percent” when compared with the single-item selling price during non-promotional periods.

As for products of the same brand available in different pack sizes, there were instances during certain periods where the “unit price” of the larger pack was up to 35 percent higher than that of the smaller pack.

The council urged consumers to compare products based on their “unit price” and historical selling prices, rather than making purchases solely on the basis of promotions or pack sizes.

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In its survey of online prices, the council noted that a 150 ml sesame oil was offered under a “Buy 1 Get 1 Free” promotion by a supermarket at HK$20 ($2.54) or HK$22, which is significantly higher than the pre-promotion price of HK$10 to HK$14.

After accounting for the promotion, the average price per item was HK$10 or HK$11, representing a maximum discount of only about 29 percent compared with the pre-promotion regular price, the council said.

It also noted that during some promotion periods, the average price per item was even about 10 percent higher, showing that bulk-buy promotions may not always offer better value than purchases made during non-promotional periods.

The council said consumers should not assume that larger packs offer better value for money.

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In its survey, the council selected 15 product groups of the same brand and category but with different pack sizes within the same supermarket. Their unit prices per 100 g or per 100 ml were calculated based on net weight or volume.

Results showed that, for 7 product groups, the unit price of the larger pack was about 2 percent to 35 percent higher than that of the smaller pack during certain periods, indicating that larger packs do not necessarily offer better value at all times, the council said.

It also suggested that Hong Kong supermarkets consider adopting unit pricing policies to enhance price transparency and help consumers make more informed purchasing decisions.