Unit pricing confusion costing customers up to $1600

But the consumer group says unit pricing inconsistencies make it too confusing for the customer.

"Whether it's price tags that are too small to read, displaying different units of measurement or hiding the labels behind another sign, retailers make it difficult for consumers to find the best value product," said Choice's campaigns and policy team lead Katinka Day.

"Our investigation found several examples of how retailers trick the system to confuse shoppers. On Woolworths' website, packaged Birdseye and Jalapeno chillies were labelled differently with the unit price on packed chillies labelled 'per 100g', while the loose chillies were priced at per kilogram."

At Aldi, the cost of loose lemons and a five-pack were not possible to compare because one price was per kg while the other was priced as per item. Unless you weigh the lemons, it's hard to tell which option is cheaper."

"While some people will choose food and groceries with no plastic to limit their waste, using unit pricing can help anyone on a tight budget," said Ms Day.

"Unit prices are supposed to help consumers compare items fairly and retailers must apply them in a way that is easy to use.

"Unfortunately, the system is also only required in supermarkets that have a floor space of 1,000 square metres. Small supermarkets or other retailers such as pharmacies or hardware shops don't have to provide this essential information."

Common unit pricing issues include:

"Whether it's poorly displayed prices or products that don't have a unit price displayed, we need Australians to help demonstrate where unit pricing isn't working and show the Federal Government that the system needs to be improved," said Ms Day.