Unit price calculator
This unit price calculator converts two package sizes to a common measure and shows which offers better value. Compare cost per kilogram, litre, item, ounce, pound, cup or gallon.
Enter price and quantity for each package separately. Their starting units can differ — for example, compare 500 g with 1 kg or 12 US fluid ounces with 1 litre.
Package A · Unit price
$9.98 / kilogram
Package B · Unit price
$7.49 / kilogram
Package B is better value
Difference per selected unit: $2.49 · Saving versus the higher price: 24.95%
Formula
unit price = package price ÷ quantity converted to the selected unit
Current-value substitution
Package A: $4.99 ÷ 0.5 kilogram = $9.98 / kilogram
Package B: $7.49 ÷ 1 kilogram = $7.49 / kilogram
How to compare unit prices
- Choose the quantity type: mass, volume or items.
- Enter the price, quantity and unit for each package.
- Choose a common comparison unit, such as kilogram or litre.
- Unit price = package price ÷ quantity converted to the chosen unit.
- The package with the lower price for the same unit is the better value.
Cost per ounce example
Package A contains 12 oz and costs $4.99, so its unit price is $4.99 ÷ 12 = about $0.4158 per ounce. Package B contains 20 oz and costs $7.49, giving about $0.3745 per ounce.
Package B is cheaper by roughly $0.0413 per ounce, or about 9.9% relative to the higher unit price. The calculator keeps the unrounded values for the comparison.
Exact unit conversion factors
| Unit | Relationship |
|---|---|
| 1 kilogram | 1,000 g |
| 1 ounce | 28.349523125 g |
| 1 pound | 453.59237 g |
| 1 litre | 1,000 ml |
| 1 US fluid ounce | 29.5735295625 ml |
| 1 US cup | 236.5882365 ml |
| 1 US gallon | 3,785.411784 ml |
| 1 dozen | 12 items |
When the lowest unit price is not best
- Compare like with like: use net contents rather than packaging weight.
- A larger pack saves money only if you can use it before it expires or spoils.
- Account for quality, concentration and yield; a concentrated product may require less per use.
- Check offer terms because a displayed discount may require buying several packages.
- Currency controls result formatting only; the calculator does not fetch or convert exchange rates.
Frequently asked questions
How do I calculate price per unit?
Divide package price by its quantity in the chosen unit. A 12 oz package for $4.99 costs about $0.4158 per ounce.
How do I tell which package is better value?
Convert both packages to one measure, such as a kilogram, litre or item, then compare. The lower unit price is better value.
Can I compare ounces with pounds?
Yes. Choose mass and select a separate unit for each package. The calculator converts both using exact definitions.
How do I calculate cost per item?
Choose the Items category, then enter the package price and item count. You can also use dozen for a group of 12.
Does the calculator handle sale prices?
Enter the actual price after discount. If an offer requires multiple packages, use the combined price and quantity or compare one qualifying package.
Updated: 2026-08-16