Unit Price Calculator
Is the family size really cheaper? This unit price calculator compares two or three packages and tells you which one costs less per pound, per fluid ounce or per item, and how much you save. Enter each price with its quantity and unit; you can mix ounces and pounds, or milliliters and fluid ounces, and the calculator converts them for you.
Updated
Results
- Unit price A
- Unit price B
- Unit price CShown when package C is filled in
Results are estimates. See the methodology below.
How to use the calculator
- For package A and package B, enter the shelf price, the quantity printed on the label and its unit.
- Optionally add a package C. Fill in both its price and its quantity, or leave both empty.
- Use the same kind of unit for every package: weight (oz, lb, g, kg), liquid volume (fl oz, mL, L) or count (items, rolls, loads).
The calculator shows the unit price of each package, the best deal and how much cheaper it is per unit than the most expensive option. Unit price C only appears when you fill in package C.
How it's calculated
Each package is first converted to a standard unit, then the price is divided by that quantity:
Unit price = Price ÷ Quantity in standard units
- Weight is shown per pound (1 lb = 16 oz = 453.59237 g).
- Liquid volume is shown per fluid ounce (1 US fl oz ≈ 29.57 mL; 1 L ≈ 33.8 fl oz).
- Count is shown per item.
The savings figure compares the cheapest unit price with the most expensive one: Savings = 1 − cheapest ÷ most expensive. If two packages have exactly the same unit price, the result is a tie.
Ounces vs. fluid ounces
An ounce (oz) measures weight; a fluid ounce (fl oz) measures volume. They can't be compared directly without knowing the product's density, so the calculator asks you to stick to one kind. Cereal and coffee are labeled by weight; juice, milk and detergent by fluid ounces.
Examples
1. Three boxes of cereal
| Package | Size | Price | Unit price |
|---|---|---|---|
| A | 12 oz | $3.99 | $5.32 / lb |
| B | 18 oz | $5.29 | $4.70 / lb |
| C | 1.5 lb | $6.49 | $4.33 / lb |
The largest box wins: it's 18.7% cheaper per pound than the smallest.
2. Laundry detergent, 92 vs. 150 fl oz
$11.99 for 92 fl oz works out to about 13.0¢ per fl oz; $18.99 for 150 fl oz to about 12.7¢. The big jug is only 2.9% cheaper, so a coupon on the smaller one would easily flip the result.
3. Paper towels, 6 vs. 12 rolls
$8.99 for 6 rolls is $1.50 per roll; $15.49 for 12 rolls is $1.29 per roll, 13.8% less. If the rolls have different sheet counts, enter the total number of sheets instead of rolls for a fairer comparison.
Unit price tags in US stores
There is no federal unit pricing requirement. According to NIST, ten jurisdictions have mandatory unit pricing provisions (Connecticut, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Oregon, Rhode Island, Vermont and the District of Columbia), and nine others have voluntary ones. NIST Handbook 130 contains a model Uniform Unit Pricing Regulation that allows several units, so one tag may show price per ounce and the next price per pound. Check the unit on the tag, or let this calculator put everything on the same basis.
A lower unit price only saves money if you use it all: bulk sizes of perishables that end up in the trash cost more than they seem.
Frequently asked questions
How do you calculate unit price?
Divide the price by the quantity. A 12-oz box at $3.99 costs about 33¢ per ounce; multiply by 16 to get $5.32 per pound.
Is the bigger package always cheaper?
No. Sales, coupons and store brands often make a smaller size cheaper per unit. In the detergent example the bigger jug saves less than 3%.
Why does the calculator say the units don't match?
You mixed weight, volume and count, for example ounces with fluid ounces. Choose the same kind of unit for every package; the calculator converts within that kind.
Are stores required to show unit prices?
Only where state or local law requires it. NIST lists ten jurisdictions with mandatory provisions and nine with voluntary ones; elsewhere stores display unit prices by choice.
How do I compare toilet paper or paper towels?
Roll sizes vary, so “mega” and “double” rolls aren't comparable by count. Enter the total sheets (rolls × sheets per roll) as the quantity, with the unit set to count.
Sources
Results depend on the prices and quantities you enter. Check the net quantity on the label, which may differ from the size printed on the front of the package.