Cost per unit (or unit price) tells you how much you pay for one single item, one ounce, one pound, etc. It's the most reliable way to compare prices between different package sizes.
Cost Per Unit = Total Price ÷ Number of Units
Examples
Which is cheaper: 6-pack for $5.40 or 8-pack for $6.80?
6-pack: $5.40 ÷ 6 = $0.90 each
8-pack: $6.80 ÷ 8 = $0.85 each
The 8-pack is the better deal.
Comparing by weight
Brand A: 16 oz for $3.20 → $3.20 ÷ 16 = $0.20/oz
Brand B: 24 oz for $4.32 → $4.32 ÷ 24 = $0.18/oz
Brand B is cheaper per ounce.
When Bigger Isn't Always Better
The larger size usually has a lower unit price — but not always. Sales, promotions, and odd pricing can flip this. Always calculate; don't assume.
💡 At the store: Many grocery stores print the unit price on the shelf tag. Look for it — it saves you the math. Just make sure you're comparing the same unit (per oz vs per lb).
🎯 Practice Problems
1. A 10-lb bag of potatoes costs $4.50. What is the cost per pound?
A) $0.35
B) $0.45
C) $4.50
D) $45.00
2. Which is cheaper per ounce: 12 oz for $2.40 or 20 oz for $3.60?
A) 12 oz ($0.20/oz)
B) 20 oz ($0.18/oz)
C) Same price
D) 12 oz ($0.12/oz)
3. 36 eggs cost $7.20. What is the cost per egg?
A) $0.10
B) $0.20
C) $0.36
D) $2.00
Want more practice?
5 more problems are ready for you. Enter your email to unlock extra practice on all lessons.
No spam, ever. Unsubscribe anytime.
🎯 Bonus Practice
1. Gas costs $3.60/gallon. How much for 15 gallons?
A) $36.00
B) $45.00
C) $54.00
D) $72.00
2. Store A: 3 notebooks for $4.50. Store B: 5 notebooks for $7.00. Which is cheaper?
A) Store A ($1.50 each)
B) Store B ($1.40 each)
C) Same price
D) Store A ($0.67 each)
3. Laundry detergent: 50 oz for $6.50 or 100 oz for $11.00. Which is cheaper per ounce?
A) 50 oz ($0.13/oz)
B) 100 oz ($0.11/oz)
C) Same price
D) 50 oz ($0.065/oz)
4. A 2-liter soda costs $1.80. A 12-pack of 12-oz cans costs $5.40. Which is cheaper per ounce? (1 liter ≈ 33.8 oz)
A) 2-liter ($0.027/oz)
B) 12-pack ($0.0375/oz)
C) Same
D) 2-liter ($0.053/oz)
5. Chicken costs $3.99/lb. You need 2.5 lbs. How much will it cost?