The smallest mini plastic trash cans on the market are those that hold 2.5 gallons. It is not guaranteed that every store will have the 2.5-gallon cans, but a portion of stores carry cans that are less than 3 gallons, averaging between 2.5 and 2.6 gallons.
Some locations do not use the gallon measurement, such as Bed Bath and Beyond. Its 10-liter cans are approximately 2.5 gallons and come with a lid and foot pedal to open the lid. The cans carried by Wal-Mart and Staples are both open-topped. Wal-Mart does offer the option to buy full cases of its small 2.5-gallon cans, which can be helpful if buying for a business or multiple rooms of a house.