A self-service checkout system which weighs products with RFID labels for security. The system includes an RFID label affixed to a product, a scale for determining actual weight information for the product, and a computer which records a customer indication that the product is on the scale, transmits a signal to the RFID label while the product is on the scale, records a response from the RFID label, obtains identification information for the product using the response from the RFID label, obtains price and reference weight information for the product using the identification information, compares the actual weight information with the reference weight information, and initiates acceptance of payment if a difference amount between the actual weight information and the reference weight information is with a predetermined threshold.