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Unit Price Calculator: Compare Package Sizes

Compare price per pound, kg, liter or item. Convert package sizes, measure shrinkflation and check how much you need to use for a larger package to pay off.

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Unit Price Calculator: Compare Package Sizes
Package A
Actual product price after discounts. Exclude refundable deposits; include applicable tax consistently.
Total contents across all items in the package, in the unit selected below.
Package B
Actual product price after discounts. Exclude refundable deposits; include applicable tax consistently.
Total contents across all items in the package, in the unit selected below.

This calculation runs on our server and is not stored – neither your result nor your entry.

Example: the calculation with the default values

The defaults are example values, not an average. Enter your own numbers and press “Calculate” to run it with yours.

Package A per lb (pound)

$4.00

Package B per lb (pound)

$3.60

Change from A to B

-10.00 %

At checkout: $3.00 for A or $3.60 for B. A lower unit price does not automatically mean a smaller bill.

Your package comparison
PackageQuantityPrice
A12 oz (weight)$3.00
B16 oz (weight)$3.60

Usage break-even for B: 90.00 % of its contents. If you use all of A, you must use more than this share of B for B to remain cheaper per quantity used. Extra storage costs are excluded.

Assumptions behind this calculation

  • The comparison uses the same kind of quantity without intermediate rounding. Unit prices display up to four decimal places. It assumes equivalent products and full use. The package price remains what you pay at checkout.

How we calculate

Total price divided by quantity gives unit price. Before comparing, we convert both quantities to the same unit. Weight and volume are different kinds of quantity and cannot be compared directly.

Savings equal the unit-price difference divided by the higher unit price. Change from A to B instead divides by the unit price of A. Those percentages use different bases. A percentage change cannot be calculated when A is free.

The usage break-even share for B is its unit price divided by the unit price of A. At that share the costs tie; above it B is cheaper if all of A is used. Equivalent quality and no additional storage costs are assumptions. Defaults are invented examples.

When A uses oz or lb, prices display per pound; for g or kg, per kg; for mL or liter, per liter. US fl oz means US fluid ounces, never Imperial fluid ounces or weight ounces. Item comparisons require equivalent individual items.

The reasoning behind these numbers, with sources, is in the article: How to Compare Unit Prices at the Grocery Store.

Frequently asked

How do I calculate unit price?

Divide the total price by the quantity in a common unit. The calculator converts ounces and pounds, grams and kilograms, or compatible volume units before comparing. Item counts must refer to comparable items.

Is the larger package always cheaper?

No. In the invented example B costs 10.00 percent less for the same quantity. Its higher checkout price can still strain your grocery budget. Unused contents can cancel the advantage.

How do I calculate shrinkflation?

Enter the old package as A and the new package as B, with the price and contents for each. Change from A to B shows the unit-price difference. Keep product quality comparable.

Can I compare ounces with fluid ounces?

No. Ounces measure weight; fluid ounces measure volume. Converting between them requires density. US fluid ounces also differ from Imperial fluid ounces; this calculator uses US fluid ounces only.

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