Field guide · 2025
Unit pricing online grocery: how to compare pack sizes
Unit pricing online grocery means the website shows a standard price next to the shelf price, such as $0.40 per 100 grams. It lets you compare a small pack with a big one without a calculator. Here is how it works and how to use it.
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A unit price is the cost of a fixed amount of the product. Two rice bags may have different weights and prices, but the unit price puts both on the same scale. The lower unit price is the better value per gram, if the pack suits your needs.
Who has to show unit prices online
Australia has a mandatory rule for this, called the Unit Pricing Code. The ACCC enforces it. The ACCC guide for retailers, dated 1 October 2021, says online grocery retailers that sell the minimum range must follow it.
The rule covers online stores that sell the minimum range of food-based grocery items over the internet. That range means items from every one of these categories: bread, breakfast cereal, butter, eggs, flour, fresh fruit and vegetables, fresh milk, meat, rice, sugar and other packaged food. A small online shop with a narrow range may not show unit prices. Most large supermarket websites do.
The ACCC says it does not resolve individual complaints about unit pricing. It enforces the code as a whole.
Which unit the price uses
The code sets the unit by how the item is supplied. The ACCC guide for retailers lists these standard units.
- Items sold by weight: per 100 grams.
- Items sold by volume: per 100 millilitres.
- Items sold by length: per metre.
- Items sold by number: per item.
Some groups have their own units. Drinks are priced per litre. Cheese and flour are priced per kilogram. Herbs and spices are priced per 10 grams. Fresh produce and meat are priced per item or, if sold by weight, per kilogram. Packaged eggs are priced per 100 grams.
This matters when you scroll a page. A milk tile may say per litre, while a rice tile says per 100 grams. Never compare two different units. Check that the unit label matches before you judge which is cheaper.
A worked example with pack sizes
The ACCC guide shows how a retailer should price a 500 gram bag of rice sold for $2.00. The unit price is $0.40 per 100 grams. You get there by dividing $2.00 by five, because 500 grams is five lots of 100 grams.
The same guide shows milk on a website. A 500 millilitre bottle at $1.50 shows $3.00 per litre. A 2 litre bottle at $3.00 shows $1.50 per litre. The big bottle costs more at the checkout, but you pay half as much for each litre.
The bigger pack is not always cheaper per unit, though. Sales, loyalty prices and brand differences can flip the result. That is why the unit price is the number to read, not the pack size.
Multipacks, specials and bundles
When two or more of the same item are sold for one price, the unit price must still show. The ACCC gives this example: a 2 litre bottle of orange juice costs $4.57, so the unit price is $2.29 per litre. In a two-for-one offer, the offer must show $1.14 per litre. The single bottle keeps its original unit price. You can set each figure against other juices.
Bundles of different items do not need a unit price. A range of different items offered at one price, such as any lipstick for $5.50, does not need one either. For those, do the sum yourself: divide the price by the total grams or millilitres, then compare.
The code applies to online ads too. A unit price must sit near the selling price on the product page and on category pages that list the range. Video and audio ads similar to television or radio ads are exempt.
How to compare pack sizes in four steps
- Find the unit price. It must be close to the selling price, easy to read and clear in meaning.
- Check the unit label. Match per 100 grams with per 100 grams, and per litre with per litre.
- Look for a sort tool. The ACCC suggests online stores offer a way to sort items by unit price. Not every site does, so check the sort menu.
- Think about use. A cheaper unit price helps only if you will finish the pack before it spoils.
Unit prices are shown in dollars and cents, worked out to the nearest cent. Two items can look tied for that reason, so a gap of one cent is not a strong reason to switch.
What to do if a unit price looks wrong
Take a screenshot of the page showing the selling price and the unit price. Check the pack size on the product page. A wrong weight or a missing unit price is the usual cause.
Tell the retailer first. The ACCC enforces the code, but it says it does not resolve individual complaints. You can still contact the ACCC to report your concern.
Our own limit: the editors read published rules and guides. We did not test any retailer's website for this article.