How to compare unit prices at the supermarket
The big number on a shelf label tells you what the pack costs. The small number tells you what the food costs.
Larger Australian supermarkets must show a unit price, such as $ per 100 g, $ per kg or $ per litre, on shelf labels and in online listings under the mandatory Grocery Unit Pricing Code. It's the fastest way to compare brands and pack sizes, as long as the two labels use the same unit.
A three-step check
It's usually the smaller print at the bottom of the shelf ticket, for example "$0.90 per 100 g".
One product may be priced per 100 g and another per kg. Multiply the per-100 g figure by 10 to compare per kg. Some products, like eggs or nappies, are priced per item.
A cheaper unit price only saves money if the extra doesn't go off or get thrown out.
Worked example
Rice: 500 g for $4.50 versus 1 kg for $7.80.
| Pack | Price | Unit price per 100 g | Per kg |
|---|---|---|---|
| 500 g | $4.50 | $0.90 | $9.00 |
| 1 kg | $7.80 | $0.78 | $7.80 |
Common traps
Shrinking packs: the shelf price stays the same but the pack gets smaller, so the unit price goes up. Multi-buys: "3 for $10" is only cheaper if the per-unit price beats the single item. Drained weight: for canned fruit and vegetables, compare the drained weight if it's shown, because liquid is cheap.
✨ Key Takeaways
- Compare unit prices, not shelf prices.
- Make sure both labels use the same unit (per 100 g or per kg).
- A bigger pack is only cheaper if you use it all.
Open the unit price calculator →