Unit prices explained
Updated October 2026 · 2 min read
Quick answer
The unit price is the cost per ounce, pound or count. It is on the shelf tag and it is the fairest way to compare two packages.
Find the number
Look at the small print on the shelf tag. It says price per ounce, pound, liter or each.
Compare the same unit
Make sure both items use the same unit.
Package size matters
Shrinking packages hide price changes. The unit price shows them.
Do not forget waste
The cheapest unit price is not a deal if half spoils.
Track prices
Plenishly's price history helps you see what changed.
What is a unit price?
The unit price is the cost per ounce, pound, liter, sheet or each. It is usually on the shelf tag in smaller print next to the shelf price. It lets you compare two packages of different sizes fairly.
How do you read it?
Find the small number on the shelf tag that says price per ounce, per pound or per count. Make sure both items use the same unit. If one says per ounce and the other per pound, convert before you compare.
| Package | Price | Size | Unit price |
|---|---|---|---|
| Small box of cereal | 3.00 | 10 oz | 0.30 per oz |
| Large box | 4.80 | 18 oz | 0.27 per oz |
| Store brand | 3.60 | 18 oz | 0.20 per oz |
| Small box of cereal | 3.00 | 10 oz | 0.30 per oz |
| Large box | 4.80 | 18 oz | 0.27 per oz |
| Store brand | 3.60 | 18 oz | 0.20 per oz |
The large box is cheaper per ounce than the small one, and the store brand is cheapest.
Why does package size matter?
Companies sometimes shrink packages without lowering the price. A cereal box may go from 18 ounces to 16 ounces at the same price. The unit price shows the real change, so you can tell when something got more expensive.
What if there is no unit price?
Do the math. Divide the price by the size. Your phone calculator works. Do this for the items you buy most.
When is the cheapest unit price not the best deal?
When you do not use it all. A huge jar of mayonnaise that goes bad is more expensive than a small one you finish. Count waste. Also consider quality, nutrition and what your family will eat.
What other unit prices matter?
Per serving matters for protein foods. Per sheet matters for paper towels. Per wash matters for laundry soap. Choose the unit that matches how you use the item.
How do you save the most?
Compare unit prices on the items you buy most often. Even small differences add up over a year.
What about sales?
A sale price is not always the lowest. A store brand at its regular price may beat a name brand on sale. Check the unit price.
Frequently Asked Questions
Stores sometimes list one by weight and one by count. Do the math yourself.
No. Check the unit price.
Usually in smaller print near the bottom or the corner of the shelf tag.
Often, but not always. Check the unit price.