Everyday value
Unit Price Comparison
Normalize two or three packages to the same unit so a lower shelf price is not mistaken for a better deal.
Decision: Which package is cheaper per comparable unit?
This comparison runs in your browser. CompareMage does not send the numbers you enter to our servers.
12 oz box
Option 1
18 oz box
Option 2
Optional third
Optional
Comparison result
18 oz box is cheaper per oz.
Based on the prices you entered, the gap is $0.01 per oz (4.91%). That is a unit-price fact, not a quality verdict.
- Shared basis
- per oz
- Cheaper package
- 18 oz box
- Unit-price gap
- $0.01
- Percent gap
- 4.91%
| Package | Shelf price | Quantity | Price per oz | Result |
|---|---|---|---|---|
| 12 oz box | $3.49 | 12 ounces (oz) | $0.29 | Higher unit price |
| 18 oz box | $4.99 | 18 ounces (oz) | $0.28 | Lower unit price |
How to read the result
A lower unit price means you pay less for the same measured amount. It does not mean the product is a better fit, fresher, or worth buying in a size you will waste.
Calculated facts
Totals, differences, and break-even figures come only from the values on this page. They describe the math, not what you should do.
Decision factors
Fit, risk, time, quality, and personal constraints stay outside the calculator. A cheaper path can still be the wrong path for those reasons.
Methodology
Each package is converted to a shared base unit using fixed US customary factors (16 oz per pound, 128 fl oz per gallon, 12 items per dozen). Unit price is shelf price divided by that converted quantity. The lowest finite unit price is marked as the cheaper package. Ties are reported instead of forcing a winner.
Assumptions
- Label quantities are net contents, not serving size.
- Quality, brand, and waste are ignored. This is a price comparison, not a quality score.
- Weight and volume are never mixed.
Examples
Cereal boxes
A 12 oz box at $3.49 is $0.29/oz. An 18 oz box at $4.99 is $0.28/oz. The larger box is cheaper per ounce by about a cent.
Paper towels by count
A 6-roll pack at $12.00 is $2.00 per roll. A 12-roll pack at $21.00 is $1.75 per roll if the rolls are the same size.
How to use it
- Enter each package’s shelf price and the quantity printed on the label.
- Choose the unit that matches the label, not a guessed conversion.
- Read the unit price, the cheaper package, and the gap in dollars and percent.
Limits
- Club-pack rolls and “mega” sheets can differ in actual sheet count even when the pack count matches.
- The tool does not look up live store prices.
Questions
Why is the bigger package sometimes more expensive per ounce?
Warehouse sizes are not automatically cheaper. A sale on the smaller size, a different brand mix, or a club-pack of a premium line can invert the usual bulk discount. Unit price is the check.
Can I compare a weight label with a fluid-ounce label?
Not in this tool. Weight, volume, count, and length are different families. A 12 oz bag and a 12 fl oz bottle are not the same measurement unless you know density.
Which unit does the result use?
Weight compares per ounce, volume per fluid ounce, count per item, and length per inch. The page states the shared basis so you are not mixing pounds with grams.
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