NEW YORK (AP) - It's about to get easier to compare prices at some big online stores.

NEW YORK (AP) It's about to get easier to compare prices at some big online stores.

New York's attorney general says Costco, CVS, FreshDirect, Wal-Mart and Walgreen have agreed to list unit prices on their websites and mobile apps soon.

A unit price tells consumers how much a product costs by each unit of weight. It divides the full price of the item by the size of its packaging. For example, a 16 ounce bottle of shampoo costing $5.99 would have a unit price of 37 cents per ounce. Because the same product can be sold in several different sizes, a unit price is a better way to compare whether a giant box of cereal is really a good deal compared to a smaller one.

Unit prices are already listed in physical stores.