Australia's largest supermarket Woolworths has begun a national roll-out of comparative unit pricing making it the first national grocery retailer in Australia to display both the actual and unit price on its labels.

Following successful trials across Australia, Woolworths said it will begin to roll-out unit pricing on around 19,000 items in each of the company's 780 Woolworths and Safeway stores.

General manager of Woolworths Supermarkets, James Aylen, said unit pricing makes it easier for customers to make like-for-like price comparisons between products.

"The Woolworths unit pricing system allows customers to quickly and easily compare the prices of different sized products and brands to see which is the best value for their needs," Aylen said.

The retailer said that depending on the size or type of product, unit pricing will be shown in "easily comparable" formats such as 100 millilitres, one litre, 100 grams or one kilogram. Where applicable, some products will display the price per each single item.

"Price is one of many factors which influence customers purchasing decisions. Unit pricing provides value-driven customers with extra information that may help make more informed choices when they shop," Aylen added.

The retailer currently has unit pricing in eight stores across the country and over the next year will be updating tickets nationwide.

"Customers across Australia will first notice the new unit pricing on our weekly specials price tickets from 10 November. Meanwhile, all newly opened Woolworths stores will feature unit pricing across the store from the first day's trading," Aylen said.