About this tool
Unit Price Comparison Calculator is a free, in-browser tool that normalizes the prices of differently-sized packages to a common unit — per kilogram, per litre or per item — and highlights the cheapest option.
Each unit price is the package price divided by its quantity after converting to a common base: grams, ounces and pounds all become kilograms, and millilitres and fluid ounces become litres. The winner is the lowest unit price, and the savings figure shows how much cheaper it is than the runner-up.
Use it in the supermarket when the shelf shows a 500 g pack against a 1 kg pack, or to check whether the "family size" is really the better deal. All comparisons run locally in your browser.
Frequently asked questions
Which units can I compare?
Weight units (g, kg, oz, lb) with each other, volume units (ml, L, fl oz) with each other, and item counts with item counts. Weight cannot be compared against volume — the tool flags mixed dimensions as an error.
How are ounces and pounds converted?
1 oz = 28.3495 g and 1 lb = 453.592 g (avoirdupois); 1 US fl oz = 29.5735 ml. All weights are shown per kilogram and volumes per litre.
What does the savings percentage mean?
It compares the cheapest option's unit price with the second-cheapest: (runner-up − cheapest) ÷ runner-up × 100. That is how much less you pay per unit by picking the winner.
Do I have to fill in all three items?
No. Leave item C (or B) blank and it is skipped; with a single item the tool simply shows its normalized unit price.