Product availability can be determined using radio frequency identification (RFID) by determining whether a RFID tag is detectable by a RFID reader and setting a product availability condition, where the RFID tag is not attached to the product, and where distance between the RFID tag and the RFID reader changes as quantity of the product changes. A system for determining availability of products using RFID can comprise a product display unit, a RFID reader, a RFID tag associated with the product display unit, and a computing device configured to set product availability conditions. In the system, distance between the RFID tag and the RFID reader changes as quantity of the product changes.