How Long Does It Take to Read Passive UHF Tags?

Published: September 10, 2009

What is the total time needed for an RFID reader to interrogate passive UHF tags, and for the tags to respond?


To answer this question, I reached out to Susan Flake, Motorola‘s senior manager of retail RFID business development. According to Susan, the minimum time needed for a passive UHF EPC tag is 397.75 microseconds, and the maximum is 45,437.5 microseconds. This range assumes one tag in free air, not attached to a product or asset, and is calculated based on EPCglobal‘s air-interface protocol.

The real-world number is likely to be less, however, since it depends on how the interrogator is architected and designed, the environment in which the tag is located and the material to which it is attached. The response time also increases if there are more tags in the field, because the tags and readers must go through an algorithm enabling the interrogator to read individual tags.

—Mark Roberti, Editor, RFID Journal