How it works
How to use this unit price calculator
- Enter Pack A’s price and quantity.
- Enter Pack B’s price and quantity in the same unit (ounces, count, liters).
- Read each unit price and which pack is cheaper per unit.
Formula
The calculation formula
Unit price = Pack price ÷ Quantity01
Divide each pack price by its quantity.
02
Compare the two unit prices. The lower unit price is the better value if the items are the same product.
Worked examples
Example calculations
Larger pack wins
$4.80 ÷ 16 = $0.30. $6.00 ÷ 24 = $0.25. Pack B has the lower unit price.
Same unit price
$4.80 ÷ 16 and $9.60 ÷ 32 are both $0.30. Quantity must be greater than zero.
When to use it
Common use cases
- Compare two grocery sizes
- Check a warehouse pack against a smaller box
- See whether a sale pack is actually cheaper per unit
Limits
Assumptions and limits
- Quantities must use the same unit. The calculator does not convert ounces to pounds.
- Quality, brand, and waste are ignored. Only price per unit is compared.
- Currency display uses USD rounding to 2 decimal places.
Questions
Frequently asked questions
What if the store already prints a unit price?
Use this when two packs use different sizes or one label is missing. Enter the same unit both times.
Does a lower unit price always mean I should buy that pack?
Only if you will use the extra amount. A cheaper unit price on a size you will waste can still cost more.
Sources
Sources and review
- NIST Office of Weights and Measures — unit pricing
Unit price as the price of a consumer commodity per unit of weight, measure, or count
Accessed August 25, 2026