An Otago woman fed up with the high prices for groceries found she saved 35 per cent when she ordered her food from Australia.

The woman, who posted her shopping to Twitter, ordered 13 items online from Amazon Australia. She paid A$93.30 (NZ$99.47) for her order and received free shipping, and the order arrived in five days.

She put the same items, which included a toothbrush, toothpaste, pasta, dried fruit, nuts, and oats, into her Countdown online shopping cart, and found it would have cost her an extra $40, to a total of NZ$139.96.

Stuff put the theory to the test and filled an Amazon Australia cart with 13 items for a total of $67.88 and compared it to the same products at Countdown.

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The Amazon cart included a two-pack of Colgate bamboo toothbrushes for $4.99, 350g of roasted almonds for $5.99, three cans of Heinz spaghetti for $2 a can, 500g of San Remo elbow pasta for $1.95, and 500ml of Dove Body Wash for $8.

Fresh food such as produce, meat and dairy could not be purchased.

The total price of the cart came to $67.88 and free shipping.

Amazon run a free shipping promotion, which allowed for free shipping if certain items in the cart totalled $59. Shipping would otherwise cost $15.

Stuff only picked items covered by this promotion.

Some items could only be purchased with a minimum quantity - such as the Palmolive soap, which had a minimum quantity of two, and Heinz Spaghetti which had a minimum of 3.

Stuff then added the same products and quantities to Countdown's online shopping cart.

The total of the cart came to $80.80. The order would be delivered the next day - but had a delivery fee of $14.99 and $1 for paper bags, which bought the total to $94.80.

Almost all products were more expensive to buy at Countdown, with the biggest difference being the bamboo toothbrushes which cost $4.99 from Amazon, but $8 at Countdown.

500ml of Palmolive soap was on special at Countdown for $4, but was usually $6.

On Amazon it cost just $3.85 - but it had a minimum quantity of two.

The cost of 500ml was both $2.50 at both stores, but Amazon had a minimum order quantity of two.

Countdown has been approached for comment, but a Countdown spokesperson told Newshub there were several factors contributing to price differences.

“The main driver is how much we pay a supplier, and in the last six or seven months, we’ve had more requests for food price increases from our suppliers than we had in the last year.

“There are also other factors that could be at play too, like products which do or don’t have GST added in Australia vs New Zealand, how much it costs to get food to New Zealand, and the cost to us and our suppliers to distribute it around, both of which are seeing significant cost pressures at the moment."

Pressure on supermarkets and the price of food has come after the Commerce Commission released its final report into the grocery sector earlier in the month.

It recommended addressing imbalances in bargaining power between the major grocery retailers and suppliers through a mandatory grocery code of conduct, considering enabling collective bargaining by some suppliers, and strengthening the Fair Trading Act’s business-to-business unfair contract terms provisions.