Better Buy Comparison Calculator
Compare two package deals by unit price and see which is the better buy and how much you save per unit.
How it works
Unit price = price ÷ size · better buy = the lower unit price · cheaper by = (high − low) ÷ high × 100
The only fair way to compare two package sizes is to reduce both to a price per single unit — per item, per ounce, per sheet — and pick the smaller one. Bigger packs are usually but not always cheaper per unit, so this catches the cases where the "value" size is actually the worse deal. The "cheaper by" percentage expresses the saving relative to the pricier option’s unit price.
Worked example
Option A is $3.99 for 12 (33.25¢ each); Option B is $6.49 for 24 (27.04¢ each). B is cheaper, saving about 6.2¢ per unit — roughly 18.7% less than A per unit.
Frequently asked questions
How does the calculator decide the better buy?
It divides each price by its size to get a unit price, then picks the lower one. Comparing per-unit costs removes the distortion of different pack sizes.
What should "size" be?
Whatever unit makes the two options comparable — count of items, ounces, grams, sheets or millilitres — as long as you use the same unit for both A and B.
Is the bigger pack always cheaper per unit?
Usually, but not always. Retailers sometimes price mid-size packs below the jumbo size per unit, or run a sale on the small one. Checking the unit price is the only way to be sure.
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This calculator is for educational purposes. Double-check important results before acting on them.