Unit price calculator
Enter the price and size of two to four products. The calculator turns each into a price per ounce, pound, 100 g, liter or item and shows which one is cheapest.
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How the comparison works
For each item the calculator divides the price by the total amount (size × number of packs) and scales it to the unit you pick: per ounce, pound, 100 g, kilogram, fluid ounce, 100 ml, liter or item. Weights are compared with weights, volumes with volumes and counts with counts; ounces here are weight ounces, and fluid ounces are US fluid ounces (29.57 ml).
The cheapest item is highlighted, and every other item shows how much more it costs for the same amount. A 16% gap means you pay 16% more for every ounce you take home.
Example
A 16 oz jar of peanut butter costs $4.99 and a 28 oz jar costs $7.49. Per ounce that is $0.312 against $0.268, so the small jar costs 16.6% more for the same amount of peanut butter. Over a year of one jar a month, buying the big size saves roughly $8.
Tips for using unit prices
- Use the Packs field for multi-buy offers: three 12 oz boxes for $10 is a price of 10, size 12, packs 3.
- Many US stores print a unit price on the shelf tag, but the unit can differ between products (per ounce on one, per count on the next). Converting both to the same unit avoids that trap.
- Only buy the bulk size if you will use it before it spoils; thrown-away food erases the saving.
- For canned vegetables or fish, compare the drained weight when it is listed, since water and oil are part of the net weight.
Frequently asked questions
How do I calculate unit price?
Divide the price by the amount in the pack. $4.99 for 16 oz is 4.99 ÷ 16 = $0.312 per ounce; $7.49 for 28 oz is $0.268 per ounce, so the bigger jar is cheaper.
Is the bigger pack always cheaper?
No. Bulk sizes are often cheaper per unit, but sales on smaller packs, multi-buy deals and store brands regularly beat them. Compare the unit price instead of assuming.
How does unit price help spot shrinkflation?
When a product shrinks from 16 oz to 14.5 oz at the same price, its unit price rises about 10% even though the shelf price did not change.