What is unit price in math?
A unit price is the cost of one unit of something, found by dividing the total price by the number of units. For example, 18 dollars for 6 pounds is 18 ÷ 6 = 3 dollars per pound. It is the fairest way to compare products sold in different package sizes: the lower unit price costs less per unit.
Unit Price in a picture
Formal definition and notation
If n units of an item cost a total price P, with n > 0, the unit price is Pn, measured in money per unit (dollars per ounce, cents per item). It is the unit rate of the ratio price : quantity, and in the proportional relationship cost = unit price × quantity it is the constant of proportionality.
| Symbol | Read it as | Meaning |
|---|---|---|
| Pn | P over n | total price divided by the number of units |
| dollars per ounce | dollars per ounce | a unit price label: per means for each one |
Key facts
- Compare unit prices, not total prices: a bigger package can cost more and still be cheaper per unit.
- Only compare unit prices that use the same unit. Convert first: 16 ounces = 1 pound.
- A lower unit price means you pay less per unit; a higher one means you pay more.
- Unit price times quantity gives the total cost, so the cost of any amount is proportional to the amount.
- Money is usually rounded to the nearest cent, but keep extra decimal places while you compare two close unit prices.
Unit price formula
- total price
- what the whole package costs, in dollars or cents
- number of units
- how many items, ounces, pounds or liters are in the package
Divide by the number of units to find the price for one unit. Turn it around to find any total: total = unit price × units.
Try it: price per unit
Change the package size and its price. The dollars per 1 pound is the unit price, so you can compare packages of different sizes.
Unit Price examples, step by step
Example 1: Price of one item
A pack of 7 pens costs 8.75 dollars. What is the unit price?
- Unit price = total price divided by the number of units: 8.75 ÷ 7.
- Divide: 8.75 ÷ 7 = 1.25.
- Check: 7 × 1.25 = 8.75.
Answer: The unit price is 1.25 dollars per pen.
Example 2: Which jar is the better buy?
A 16-ounce jar of peanut butter costs 4.48 dollars. A 28-ounce jar costs 7.28 dollars. Which has the lower unit price?
- 16-ounce jar: 4.48 ÷ 16 = 0.28 dollars per ounce.
- 28-ounce jar: 7.28 ÷ 28 = 0.26 dollars per ounce.
- Compare: 0.26 < 0.28, so the big jar is cheaper per ounce, by 2 cents.
Answer: The 28-ounce jar has the lower unit price: 0.26 dollars per ounce compared with 0.28.
Example 3: Use the unit price to find a new total
At a farm stand, 5 pounds of apples cost 6.40 dollars. At the same unit price, how much do 8 pounds cost?
- Unit price: 6.40 ÷ 5 = 1.28 dollars per pound.
- Multiply by the new amount: 1.28 × 8 = 10.24.
- Check with a proportion: 6.405 = 10.248, both 1.28.
Answer: 8 pounds cost 10.24 dollars.
Common mistakes
Divide by the number of units to find the price for one unit. Price goes on top; 0.40 is notebooks per dollar.
Total price ignores how much you get. Unit price puts both packages on the same 1-unit scale.
Unit prices can be compared only when they use the same unit.
Not to be confused with
A unit rate compares any two quantities per 1 unit, such as 50 miles per hour. Unit price is the special unit rate where the first quantity is money: 3 dollars per pound.
The total price is what you pay for the whole package (5.40 dollars for 20 ounces). The unit price is what each unit costs inside it (0.27 dollars per ounce).
Quick check: 3 questions
Three pounds of grapes cost 7.50 dollars. What is the unit price?
Answer: A. 7.50 ÷ 3 = 2.50 dollars per pound. Choice B divides pounds by dollars, C multiplies, and D subtracts.Show answer and explanation
Which package of juice cans has the lowest unit price?
Answer: C. Per can: 4.20 ÷ 6 = 0.70, 3.00 ÷ 4 = 0.75, 6.50 ÷ 10 = 0.65, 8.04 ÷ 12 = 0.67. The 10-can pack is lowest. Choice B has the lowest total price but the highest unit price.Show answer and explanation
Rice costs 2.40 dollars per pound. How much do 4.5 pounds cost?
Answer: D. Total = unit price times units: 2.40 × 4.5 = 10.80 dollars. Choice A adds, B divides 2.40 by 4.5, and C divides 4.5 by 2.40.Show answer and explanation
Unit Price: frequently asked questions
How do you calculate unit price?
Divide the total price by the number of units. A 12-pack of water for 4.20 dollars has a unit price of 4.20 ÷ 12 = 0.35 dollars per bottle. Use the same unit for every product you compare, such as ounces, and keep at least three decimal places when the prices are close.
Is the lower unit price always the better buy?
In math terms, yes: a lower unit price means each unit costs less. In real life you may also think about other things. If a big package would go to waste, you could pay more in total for food you never use. Questions on tests ask about unit price only, so the lower unit price is the answer.
How do you compare unit prices with different units?
Convert one price so both use the same unit. To compare 0.20 dollars per ounce with 3.00 dollars per pound, use 1 pound = 16 ounces: 0.20 × 16 = 3.20 dollars per pound. Now 3.00 is less than 3.20, so the price per pound is the better deal.
Practice and tools
Sources
- Common Core State Standards, Grade 6 Ratios and Proportional Relationships (6.RP.A.3.b, unit pricing)
- OpenStax, Prealgebra 2e, 5.6 Ratios and Rate (unit price)
Updated November 2026·Reviewed by the Effortless Math team·Standards: CCSS 6.RP.A.3.b
Cite this entry
Effortless Math Team. “Unit Price.” Effortless Math Dictionary. Updated November 2026. https://www.effortlessmath.com/math-dictionary/unit-price/
Flashcard
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