 And it helps you to compare two products of different sizes. So here you can see that the 16-ounce cereal is priced 5.19 for the whole unit, which ends up being 31 cents per ounce. In this, you can see the 12-ounce cereal is 2.99 for the entire product, but it comes out to be 24 cents per ounce. So this is the better buy. So the next time you're at the store, remember to check the unit price to find out which size your product is the best buy.