Compare equal units
Suppose one bottle costs $5.79 for 12 fluid ounces and another costs $8.49 for 20 fluid ounces. Divide each price by its size.
| Package | Price ÷ size | Price per fl oz |
|---|---|---|
| 12 fl oz | $5.79 ÷ 12 | $0.4825 |
| 20 fl oz | $8.49 ÷ 20 | $0.4245 |
The 20-ounce bottle costs about 12% less per fluid ounce, even though it costs $2.70 more upfront. At 20 ounces of use, that lower unit price represents about $1.16 in savings compared with buying the same amount at the smaller bottle’s rate.
When the cheaper unit price is not the better choice
- Compare the same product or similar quality in the same unit. Ounces by weight and fluid ounces are different measures.
- Consider how much you will actually use before it expires or goes to waste.
- Check whether a promotion or delivery charge changes the checkout total.
Simple check: Unit price tells you the cost of an equal quantity. It does not tell you whether the larger package fits your budget or needs.
Enter both prices and sizes in the unit price calculator to compare your own packages.