How to compare unit prices
Unit price is the cost per single unit, such as per litre, per 100 grams or per item. Comparing unit prices is the honest way to tell which package is actually cheaper, since a bigger box is not always better value. This calculator works out the price per unit for two products and tells you which one wins.
The formula
Unit price = total price / quantity. The lower unit price is the better value.
Worked example
Product A costs 5 for 500 g, so 0.01 per gram. Product B costs 3 for 250 g, so 0.012 per gram. Product A is cheaper per gram, even though it costs more on the shelf.
Frequently asked questions
How do I compare which is cheaper?
Divide each price by its quantity to get the cost per unit, then compare. The lower cost per unit is the better value, regardless of pack size.
Why is the bigger pack not always cheaper?
Retailers sometimes price larger packs at a higher unit cost. Checking the price per unit is the only reliable way to spot the real bargain.
What units should I use?
Any unit, as long as both items use the same one. Grams vs grams, or litres vs litres. Convert first if the packs use different units.
Is the bigger pack always cheaper?
Usually, but not always. Retailers sometimes price mid-size packs worse than small ones, which is exactly what this tool catches.
Can I compare by piece?
Yes. Enter the number of pieces as the size to get a price per piece.