Pak'n Save has been named the country's cheapest supermarket - for the 11th year in a row.

And, the no-frills chain is not only the cheapest but it has beaten its main competitors by up to 10 per cent.

The latest Consumer NZ survey compared the prices of 40 identical items at supermarkets in seven centres.

Consumer NZ chief executive Sue Chetwin said Pak'n Save had dominated the survey for the past 11 years, with this year's prices being 6 per cent to 10 per cent cheaper than the competitor in each centre surveyed.

"If you are just looking for the basics, Pak'n Save is good - why would you shop somewhere else?"

Competition for second and third places was tight between New World and Countdown in the South Island, Wellington, South Auckland and Tauranga, with only a few dollars separating them.

New World was a clear second over Countdown in Auckland's North Shore but Countdown reversed this in Palmerston North.

Ms Chetwin said the difference between the cheapest and most expensive shopping trolley was the greatest in Christchurch and the least in Auckland.

On the North Shore, prices ranged from $125 for the 40 items at Pak'n Save in Albany to $145 at Foodtown Glenfield.

Filling the trolley at Pak'n Save Sylvia Park cost $129 while it was $140 at New World Botany.

Shopping around for milk proved worthwhile - you could save more than a dollar on a two-litre bottle in Auckland. Food prices went up 5.5 per cent in the year to March.

Foodstuffs Auckland, which owns Pak'n Save, said it was proud the chain had the lowest food prices for an entire decade.

"We're conscious that many Kiwis are struggling in the current economic conditions, and Pak'n Save offers significant savings for them, so shoppers can get more bang for their buck," said managing director Murray Jordan.

He added that New World was also "holding its own" against its rivals - proving competition is tight between the supermarket brands.

A spokesman for Progressive Enterprises, which owns Woolworths, Countdown and Foodtown, said the survey showed that shopping around for specials was the best way to save money.

Spokesman Luke Schepen said the company was about providing a good range of products - everything from "the basics right through to products that some other supermarkets might not have".

MORE OR LESS? IT'S YOUR CHOICE

Consumer NZ's tips for shopping:

* Don't shop when hungry.
* Know your local supermarket layout to avoid temptations.
* Take a list and stick to it.
* Join a loyalty programme to maximise discounts.
* Don't buy items just because they seem like bargains.

Cost of 40 items in Auckland:

$125 Pak 'n Save Albany
$129 Pak 'n Save Sylvia Park
$138 New World Albany
$140 New World Botany
$144 Countdown Glenfield
$145 Foodtown Glenfield