Best buy by unit price
When comparing products with different package sizes, the best buy is the one with the lower unit price. The unit price tells you how much you pay for 1 unit of the item, such as 1 ounce, 1 pound, 1 liter, or 1 item.
Method
- Identify the total cost and the amount for each option.
- Divide the cost by the number of units to find the unit price.
- Unit price = total cost ÷ number of units
- Compare the unit prices.
- The smaller unit price means the better buy.
- If needed, write the answer exactly and in simplest form.
Example check
If one package costs 6 for 3 units, its unit price is 2 per unit. If another costs 10 for 5 units, its unit price is also 2 per unit. In that case, neither is a better buy; they are equal.
How to check your work
- Make sure you divided in the correct direction: cost ÷ amount, not the reverse.
- Compare prices using the same unit.
- If your answers are fractions, simplify them if possible.
- The option with the smaller unit price is the best buy.