The price on the shelf tells you what a package costs. The unit price tells you what you're really paying. Here is how to use it, and when the cheapest unit price still isn't the best buy.
A $3.20 jar looks cheaper than a $7.20 jar, but if the small one holds 16 oz and the big one 40 oz, you pay $0.20 per ounce for the small jar and $0.18 for the big one.
Package sizes vary so much that the shelf price on its own rarely tells you which is the better value.
Many stores print a unit price on the shelf tag, usually in smaller text next to the main price. Before you compare two tags, check that they use the same unit:
If the units don't match, convert one of them, or work the unit prices out yourself.
Three conversions cover most grocery shopping:
Recheck the unit price whenever a price changes. A 12 oz box at $3.00 and a 24 oz box at $5.40:
The big box wins. But with a $1 coupon on the small box, it costs $2.00, which is 2 ÷ 12 = $0.167 per ounce. Now the small box is the better deal. Work out the sale price with the Percent Off Calculator, then compare unit prices.
For things you use up, like detergent, the best unit is the use, not the ounce, because concentrations differ. Laundry detergent bottles list the number of loads:
In the calculator, set the unit to items and enter the number of loads, servings or sheets as the quantity.
The lowest unit price only saves money if you use what you buy:
Which is the better deal? Open each answer to check.
Compare while you shop. The Unit Price Calculator converts units and compares up to 4 products at once.