Pak N Save and Countdown have come out on top as the cheapest supermarkets in the country, according to results from Consumer NZ's largest supermarket survey.

The survey compared prices of the 40 top-selling items at supermarkets in Tauranga, north and southeast Auckland, Napier/Hastings, Wellington, Christchurch and Dunedin.

Countdown supermarket chains are the second cheapest place in Consumer NZ's new survey.

While Pak N Save remains New Zealand's cheapest supermarket chain, Countdown came in second, nudging New World into to third place.

According to survey results, Dunedin's Hillside Road Pak N Save is the cheapest supermarket in the country, while the most expensive supermarket is New World Chaffers in Wellington.

Consumer NZ says items bought differed between centres because of substitutions.

Consumer CEO Sue Chetwin says mystery shoppers commented on the number of discounts and multi-buys they found in Countdown – what she believes is the secret of the chain's rise to second place.

'Some of the discounts were huge - you could save $2.49 on a pack of instant coffee.”

For 10 basic items – such as sugar, milk, butter and flour – shoppers bought the cheapest brand. For seven out of 10 basic items Pak N Save was the cheapest.

The 40 items included food and non-alcoholic drinks, personal care and cleaning items.

Alcohol, fresh meat, fish or produce were not included in the survey.

Buying online from Countdown proved the most expensive way to buy the 40 items at $160 including $13.25 for delivery.

Sue says by picking up the groceries the cost drops.