The cost of a basic weekly shopping trip for a household of a man and woman and two teenagers will set them back an average of $231 per week, an annual food costs survey has found.

The Estimated Family Food Costs Survey has been prepared every year since 1972 by student dietitians at Otago University.

Surveys were carried out at four supermarkets each in Auckland, Hamilton, Wellington, Christchurch and Dunedin.

The cost of food for a man was on average about $50 per week, while women ate an average of $48 worth. Adolescent boys were the most expensive to feed, costing $64 per week, while girls cost $53.

A 10-year-old child ate $43 worth of food per week, a five-year-old cost $29 to feed and children aged between one and four cost between $24 and $27 each week for food.

However, non-food items could expect to add about $16 each week on a basic budget, $30 per week on a moderate budget, and $48 on a high-end budget, for a family of four.

The average cost of a basic weekly shopping expedition could therefore be expected to set a family, of a man and woman with a girl and a boy aged in their teens, back $231.

The food costs were based on a basic shopping list that assumed food would be eaten at home using few pre-prepared items, and certain items would be chosen only when in season.

Households that upgraded their shopping list to include more expensive cuts of meat and a greater variety of fruits and vegetables could expect to pay a further $15 per person -- raising the average cost of food to the family with two teenagers, to $275 per week, and $291 if basic non-food items are included.

A further $10 per person per week could be added if a greater range of pre-prepared items were included in the food shopping -- costing the family with teenagers $315 each week in food, or $331 with basic non-food items.

Those shopping on a generous budget could pay up to $363 per week for a family with teenagers.

The survey found the price did not vary significantly between regions, as supermarket chains kept prices similar in each centre.

"Consumers can shop more economically at supermarkets, but the extra costs - ranging from $1 to $6 per person, depending on region - of shopping at local specialty shops may be worthwhile if the cost of travel to a supermarket is weighed against walking to a smaller local outlet," the surveyers said.

The surveyers also noted that many families and individuals spent less weekly than the estimated costs in the survey, but that not including some of the basic items could restrict a balanced diet.

"The risk of consuming a diet which does not meet New Zealand recommendations for good health, increases as expenditure falls below this."