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RFID, short for radio-frequency identification, uses electromagnetic frequencies to communicate between RFID readers and RFID tags. RFID readers, transmit signals to read and write data on RFID tags. There are both active and passive tags. Active tags utilize batteries to boost their power output.

The physical tag read range is determined by the individual RFID reader and antenna power, the material and thickness of material the tag is coated or covered with, the type of antenna the tag uses, the material the tag is attached to and more!

While a specification may show a theoretical RFID tag read range of 5 meters (ideal conditions) it may be as little as 1 meter if the tag is attached to an object that is sitting on a metal surface surrounded by water and electromagnetic waves (not ideal conditions)!

Far-range UHF RFID tags can read at ranges as far as 12 meters with a passive RFID tag, whereas active tags can achieve ranges of 100 meters or more. The operating frequency of UHF RFID tags ranges from 300 MHz to 3 GHz, and UHF tags are the most vulnerable to interference.

It depends on the type of RFID system being used. A high-frequency (HF) reader based on the ISO 14443 air-interface protocol standard, designed for short-range transmission, has a maximum read range of about 18 inches. An active RFID system can read tags from 1,500 feet away or more, as the tags broadcast a signal and the systems are designed for longer-range applications.

Even within one type of RFID, however, there can be a wide array of read ranges. A passive ultrahigh-frequency (UHF) reader has a range of about 10 feet, while a model using a beam-steerable phased-array antenna can interrogate passive tags at a distance of 600 feet or more.

Keep in mind that the reader is only half of the story. A very small passive tag with a small antenna harvests less energy from and reflects less energy back to a reader. It, therefore, has a shorter read range than a tag with a much larger antenna.