What this tool does
The Unit Price Calculator helps you compare two products of different sizes and see which one is actually the better value. Stores love to package the same product in many sizes at prices that are hard to compare in your head. This tool does the math for you, showing the true cost per unit for each option. It is handy for grocery shoppers, budget-conscious families, and anyone who wants to stop overpaying for the wrong size.
How to use it
- Enter the Item A price and the Item A size/quantity for your first product.
- Enter the Item B price and the Item B size/quantity for your second product.
- Make sure both sizes use the same unit (both grams or both milliliters, for instance).
- Click Calculate to see the unit price of each item and which one is the better value.
A quick worked example
Say you are choosing between a 500 g pack at 5 and a 900 g pack at 8. Put 5 and 500 into the Item A fields, then 8 and 900 into the Item B fields. The first works out to 0.010 per gram and the second to about 0.0089 per gram, so the 900 g pack wins. The gap looks small per gram, but it adds up across a full cart, which is why checking the unit price pays off.
This calculator runs entirely in your browser. Your numbers stay private, it is completely free, and it needs no sign-up.
Frequently asked questions
- What is unit price?
- Unit price is the cost of one standard unit of a product, such as one gram, one liter, or one item. Dividing the total price by the size gives you a fair way to compare packages of different sizes.
- Why isn't the bigger pack always cheaper?
- Larger packs often cost less per unit, but not always. Promotions, brand differences, and packaging can make a smaller pack the better deal, which is exactly what this calculator reveals.
- Do both items need the same unit?
- Yes. For an accurate result, enter both sizes in the same unit (both in grams, or both in milliliters, for example) so the unit prices are directly comparable.
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Last updated: June 17, 2026