How unit price works
A unit price is the price divided by how much you get. It turns packages of different sizes into one comparable number, like cents per fluid ounce or dollars per pound.
Example. A 12-pack of 12 fl oz cans costs $7.99. That's 144 fl oz, so the unit price is 5.55¢ per fl oz.
A 2-liter bottle costs $2.49. Two liters is about 67.6 fl oz, so the unit price is 3.68¢ per fl oz.
The 2-liter is the better deal by about 51% per ounce, even though the 12-pack looks like the bulk buy.
Weight ounces and fluid ounces are different
An ounce measures weight and a fluid ounce measures volume. They line up for water but not for most other things, so a product sold by weight can't be compared fairly with one sold by volume. If you mix them, the calculator will warn you instead of guessing.
Multipacks
For a multipack, enter the number of items in "How many" and the size of one item in "Size." A 6-pack of 16.9 fl oz bottles is 6 × 16.9. For a single package, leave "How many" at 1 and enter the full size.
For store owners
Unit pricing works in both directions. Shoppers use it to find the best deal, and you can use it to make sure your sizes are priced in a sensible ladder, with bigger packs costing less per ounce than smaller ones. When a large pack ends up costing more per ounce than a small one, shoppers notice. Some states and cities also have rules about showing unit prices on shelf tags, so check what applies where you are.
Conversion reference
| Unit | Equals |
|---|---|
| 1 pound (lb) | 16 oz |
| 1 ounce (oz) | 28.35 g |
| 1 kilogram (kg) | 35.27 oz (2.205 lb) |
| 1 fluid ounce (fl oz) | 29.57 mL |
| 1 liter (L) | 33.81 fl oz |
| 1 pint (pt) | 16 fl oz |
| 1 quart (qt) | 32 fl oz |
| 1 gallon (gal) | 128 fl oz (3.785 L) |
All volume units here are US customary.
Common questions
- Why do some prices show in cents?
- Unit prices are often a fraction of a dollar per ounce, so they read more clearly in cents, the way most shelf tags show them. 5.55¢ per fl oz is the same as $0.0555.
- Can I compare items sold by count?
- Yes. Choose "count" as the unit to compare price per item, for example a 20-count pack of batteries against a 4-count.
- Does this include sales tax or deposits?
- No. Enter shelf prices before tax and deposits so every item is compared the same way.
Last updated October 11, 2026.