A Woolworths customer has revealed her trick to help her save on her weekly shopping trip to the supermarket.

Mum Biance shared the information on a popular Facebook page, explaining that she "always reads the fine print" on supermarket labels to compare the unit price. 

“If you’re trying to get the biggest bang for your buck, then shop by the unit price,” explained Bianca on the Mums Who Budget & Save group.

“Read the fine print on the ticket and see how much the item costs per 100g or whatever they break it down into.

“Then compare it with a different brand or similar item.

“Even though an item may seem cheaper as a whole, often you can save by buying something that’s a little bit more expensive but lasts longer or gives you more.

“Good example is Coke.

“When the 1.25L bottles are on ‘special’ they are still usually always more expensive than the 2L bottles are [at] full price if you look at the dollar per litre.

“At a glance, you’d think you’re getting a deal with the ‘special’ but you’re really not.

“Unless you specifically need a 1.25L bottle than you’re better off getting the 2L.”

Many shoppers agreed that it was the best way to save money on your bill.

“Yes! Taught my partner the same principle - things aren’t always as cheap as they appear!” said one.

Added another: “This is a great way to save money in the long run.”

Said a third: “My partner had never heard of this until I explained it. Either had my mum!”

Bianca pointed out that it's important to keep your family's needs in mind while shopping.

“Obviously this is only if you’re wanting to get the most out of the item,” she wrote.

“Otherwise it may suit your lifestyle more to buy the smaller but cheaper item, paying more upfront but replacing the item more often.”