Q. Can you explain how unit pricing works?

A. Unit pricing makes it easy for you to compare the price and value of similar foods against the same weight or volume. On the shelf label next to the actual price, you'll now spot the price per kg, per 100 grams, per kilo, per 100 mL, per litre or per item for a multi-pack.

It was introduced into large supermarkets in Australia in 2009 but the concept is widely accepted in Europe and the US.

Small corner stores and supermarkets less than 1,000 square metres are exempt.

We're used to seeing bananas at $5 a kilo but how can you compare different sizes and volumes on different packs to get the lowest price? How would you know which is better value - a large 1 kg box of breakfast cereal that costs $4.50 or the smaller 750 g pack at $4.00?

With unit pricing, you don't need to take a calculator with you when shopping or make complicated calculations to work out what is better value.

Example - two sizes of juice

With unit pricing, here's how to decide what's better value - a 2.5 litre container of orange juice costing $4.99 or a 1.5 litre container costing $3.99?

Orange juice 1 - the 2.5 litre container
2.5 L @ $4.99 so its unit price is $1.99 per litre

Orange juice 2 - the 1.5 litre container
1.5 L @ $3.99 so its unit price is $2.66 per litre

You can see that Orange juice 1 is a cheaper buy than Orange juice 2.

The unit price of $1.99 per litre for Orange Juice 1 is better value than Orange Juice 2 at a unit price of $2.66 per litre.

Generally larger packs are better value - but not always. It pays to check out the Price per 100 g or per 100 mL and compare.