When selecting RFID tags, many engineers and purchasing personnel focus on chip model, operating frequency, reading distance, and communication protocol. However, some technical documents also introduce the concept of RFID Tag Class. For those new to RFID technology, the distinction between Class 0, Class 1, Class 2, and Class 3 can be easily confusing.
Early, the EPC (Electronic Product Code) system introduced different categories from Class 0 to Class 5 to differentiate RFID tags with different functions. As RFID technology standards have matured, the most common tags in industrial applications today are UHF RFID tags based on EPC Class 1 Gen 2 (EPC C1G2) and the ISO/IEC 18000-6C standard. The earlier Class 0 and Class 1 classifications are more used to understand the development history and functional evolution of RFID tags.
What is an RFID Tag Class?
An RFID Tag Class can be understood as a classification method for the functional levels of RFID tags. It is mainly classified according to the tag's data storage capacity, read/write method, power supply type, and function. The most basic RFID tag is typically a passive RFID tag. It has no internal battery and relies on radio frequency energy emitted by an RFID reader to activate the chip, then returns data via backscatter. These tags are low-cost and long-lasting, and are widely used in retail inventory management, logistics tracking, asset management, and smart manufacturing.
As application demands increase, RFID tags have gradually added more capabilities, such as:
larger user data storage space;
rewritable data areas;
built-in sensors for temperature, pressure, vibration, etc.;
active communication capabilities.
Therefore, RFID Tag Class essentially describes the evolution of tags from simple identification to intelligent sensing nodes.
RFID Tag Class Classification Introduction
Class 0 RFID Tag: Class 0 is one of the earliest UHF RFID tag categories, a typical read-only passive RFID tag. The data in these tags is usually written during the manufacturing stage, and users cannot modify the information. The tag is mainly used to provide unique identification, such as an EPC (Electronic Product Code).
Class 0 tags are simple in structure and low in cost, but their flexibility in supply chain management is limited because they cannot be written to on-site. With the development of the EPC Gen2 standard, Class 0 tags have gradually been replaced by more advanced tag types.
Class 1 RFID Tag: Class 1 is a widely used type of tag in the development of RFID. Its main feature is Write Once Read Many (WORM). Unlike Class 0, Class 1 tags allow users to write data once during the production or deployment phase, such as product numbers, batch information, or asset IDs, but this data cannot be modified afterward.
In early retail supply chain RFID projects, Class 1 tags were widely used because they could meet the requirement of unique product identification while maintaining low cost. Furthermore, the EPC Class 1 Gen 2 standard further optimized communication efficiency, anti-collision mechanisms, and global compatibility, becoming the mainstream standard in current UHF RFID applications.
Class 2 RFID Tag: Compared to the previous two types, Class 2 RFID tags have stronger data processing capabilities and are read-write passive RFID tags. Users can read and write to the tag's storage area multiple times according to application needs. For example, in industrial asset management, information such as equipment maintenance records, inspection times, and production status can be written to RFID tags.
Class 2 tags typically have larger storage space, making them suitable for applications requiring dynamic data updates. However, in modern RFID projects, many similar functions are already implemented through the User Memory area of EPC Gen2 tags. Therefore, the concept of Class 2 is not as commonly used in actual procurement as EPC Gen2 chip models.
Class 3 RFID Tags: Class 3 RFID tags represent the development of RFID from simple identification to data collection. These tags typically have sensor functions, such as temperature monitoring, pressure detection, and vibration recording, and may be combined with batteries to form semi-passive RFID tags. For example, in cold chain transportation, Class 3 RFID sensor tags can record temperature changes during transportation. When the goods arrive at their destination, staff can use an RFID reader to obtain historical temperature data, thereby determining whether the product has experienced abnormal environments.
Compared to ordinary passive RFID tags, Class 3 tags provide more environmental information, making them suitable for scenarios such as food cold chain, pharmaceutical transportation, and monitoring of high-value equipment.
Class 4 RFID Tags: Class 4 RFID tags are active RFID tags. Unlike passive RFID tags, Class 4 tags have an internal battery and can actively transmit wireless signals instead of waiting for RFID reader activation. Due to their active communication capabilities, Class 4 tags typically have a longer communication range and can be used in scenarios requiring real-time monitoring, such as personnel positioning, vehicle management, and industrial asset tracking.
For example, in large manufacturing plants, installing battery-powered active RFID tags can continuously broadcast equipment locations, enabling real-time monitoring of production resource status. However, active RFID tags are more expensive, and battery life and maintenance issues need to be considered; therefore, they do not completely replace passive RFID tags.
Class 5 RFID Tags: Class 5 is the highest-level RFID tag class, possessing not only active communication capabilities but also the ability to communicate with other RFID tags or external devices. From a design perspective, Class 5 tags are closer to smart devices with network node capabilities than traditional RFID tags.
This technology supports data exchange between tags and more complex IoT applications. However, due to its higher system complexity and cost, its practical commercial applications are currently relatively limited.
How should modern RFID applications choose tag types?
In actual RFID project design, it is not recommended to choose RFID tags solely based on Tag Class. Instead, an evaluation should be conducted based on the application environment and data requirements. If the project's primary requirements are rapid identification and inventory management, such as warehouse inventory counting, apparel retail management, pallet tracking, and logistics transportation management,
EPC Class 1 Gen2 UHF RFID tags are typically sufficient. These tags offer longer reading distances, lower costs, and a mature supply chain ecosystem.
If the project requires recording environmental data, such as cold chain temperature monitoring, medical supply transportation, and industrial equipment condition monitoring, then RFID sensor tags with sensing capabilities should be considered.
If the application requires real-time positioning, such as AGV vehicle tracking or valuable equipment location, active RFID tags or a hybrid BLE RFID solution may be more suitable.
Therefore, RFID tag class is more of a technical classification method than the sole selection criterion during procurement. Engineering projects typically require a comprehensive assessment considering protocol, frequency, chip performance, installation method, and application environment.
