Want to know you are buying the cheapest groceries?

You can, if you shop at Aldi.

Yesterday the discount grocer began displaying the price per unit of measure for all products alongside the retail price, making it easier for consumers to compare prices on different products and pack sizes.

Choice, the magazine for the consumer lobby group the Australian Consumers Association, has been asking for unit pricing for years, pointing out it is compulsory in Europe.

But so far the big retailers Coles and Woolworths have resisted, although Woolworths will introduce it next year.

Woolworths already has unit pricing in New Zealand and will start with several trials in stores next year.