Unit Price Calculator
Compare pack sizes and find which one is cheapest per gram, millilitre or item.
About this tool
Converts each item to a price per 100 g, per 100 ml or per item and highlights the cheapest. Weights and volumes in different units (g, kg, oz, lb, ml, l) are converted automatically.
Bigger packs are not always cheaper, and promotions on one size can make a smaller pack the better deal. Shelf labels do not always show a unit price, and when they do the units can differ. Enter the price and size of up to four items, and the calculator works out the price per 100 g, per 100 ml or per item, highlights the best value and shows how much cheaper it is.
How to use the Unit Price Calculator
- Enter the price and the pack size of each item you want to compare.
- Choose the unit for each size: grams, kilograms, millilitres, litres, ounces, pounds or individual items.
- Leave unused rows empty.
- Read the unit price for each item; the best value is shown in bold.
500 g for 3.49 or 1 kg for 5.99
A 500 g pack at 3.49 costs 3.49 ÷ 5 = 0.698 per 100 g. A 1 kg pack at 5.99 costs 5.99 ÷ 10 = 0.599 per 100 g, which is about 14.2% cheaper per gram. If the smaller pack were on special at 2.75, it would cost 0.55 per 100 g and become the better buy.
Getting the most from unit prices
A unit price puts every product on the same scale, usually per 100 g, per kilogram, per 100 ml, per litre or per item. Compare like with like: the same brand in different sizes, or similar products from different brands. Only compare items measured the same way, since weight and volume are different (a litre of honey weighs about 1.4 kg). A cheaper unit price is only a saving if you will use it all before it goes off, and multi-buy deals are only worth it for things you would buy anyway. For drained products such as tinned vegetables, the drained weight on the label gives a fairer comparison.
Frequently asked questions
Why are the prices shown per 100 g?
It keeps the numbers easy to read for everyday groceries. The ranking would be the same per kilogram.
Can I compare ounces with grams?
Yes. Ounces and pounds are converted to grams, and litres to millilitres, before comparing.
Can I compare a weight with a volume?
No. They measure different things, so the calculator asks you to compare items in the same kind of unit.
What about multi-packs?
Enter the total size, for example 6 × 330 ml as 1980 ml, and the total price.