An RFID tag (radio-frequency identification tag, also called a transponder) is a small device made of a microchip and an antenna. When a reader sends out a radio signal, the tag answers with its unique identifier, so software can tell exactly which object the tag is fixed to. Most tags used for asset tracking are passive: they have no battery and run on the energy of the reader's signal.
The chip and antenna are usually printed or bonded onto a thin film called an inlay. The inlay is then packaged for the job: a paper or polyester label, a rigid hard tag, a cable tie, a key fob, a laundry tag, or an on-metal tag built to work on steel. If you are choosing tags to buy, see the RFID tags and asset labels in the Asetavo store.
How an RFID tag works
- The reader transmits. A handheld or fixed reader sends a radio signal through its antenna.
- The tag wakes up. A passive tag's antenna collects energy from that signal, enough to power the chip for a moment.
- The tag replies. The chip sends back its identifier. UHF tags do this by backscatter, reflecting a modulated version of the reader's signal. HF and LF tags use load modulation of the reader's magnetic field.
- Software looks it up. The ID on its own is just a number. The asset register links it to a real item, such as "Projector AV-014, Training Room 2".
Types of RFID tags
| Type | Frequency | Typical passive read range | Common standard | Typical uses |
|---|---|---|---|---|
| LF tag | 125–134 kHz | A few centimeters | ISO 11784/11785 (animal ID) | Access fobs, animal ID, some tool marking |
| HF / NFC tag | 13.56 MHz | A few centimeters, up to about 1 m with large antennas | ISO/IEC 14443, ISO/IEC 15693 | Payment and ID cards, library books, tap-to-identify with a phone |
| UHF tag | 860–960 MHz (regional bands) | Several meters; often 5–10 m with fixed antennas | EPC Gen2 / ISO/IEC 18000-63 | Asset audits, retail, logistics, doorway detection |
| Active tag | Varies (often UHF or 2.4 GHz) | Tens of meters or more | Vendor-specific | Containers, vehicles, high-value mobile equipment |
Tags are also grouped by power source:
- Passive: no battery; powered by the reader. Cheap, thin and long-lived. The standard choice for asset tagging.
- Active: has its own battery and transmits by itself. Longer range, but a much higher cost per tag and batteries to replace.
- Battery-assisted passive (BAP): a battery runs the chip, but the tag still replies by backscatter. It improves sensitivity, often for sensor tags.
What is stored on an RFID tag
A passive UHF tag has four memory banks. The EPC bank holds the writable ID your software uses. The TID bank holds the chip's factory-set identity, which cannot be changed. There is also optional user memory and a reserved bank for passwords. HF and NFC tags carry a factory UID. Good practice is to store only an identifier on the tag and keep the description, location and owner in the register, because those details change and the tag should not have to.
RFID tag vs RFID label vs barcode label
| Item | RFID label | RFID hard tag | Barcode or QR label |
|---|---|---|---|
| What it is | Inlay inside a printable label | Inlay sealed in plastic, epoxy or metal housing | Printed code, no chip |
| Read without line of sight | Yes | Yes | No |
| Many at once | Yes (UHF) | Yes (UHF) | No, one scan at a time |
| Durability | Indoor, low wear | Outdoor, industrial, washing, heat | Depends on label stock |
| Works on metal | Only on-metal versions | On-metal versions available | Yes |
| Relative cost | Low | Higher | Lowest |
Examples of RFID tags in asset tracking
- IT equipment: UHF labels on laptop lids and monitors, so a storeroom can be counted with one walk-through.
- Tools and machinery: on-metal hard tags riveted or glued to steel toolboxes, generators and compressors.
- Hospital equipment: durable tags on infusion pumps and wheelchairs, read at ward doorways.
- Furniture and AV kit: low-cost labels where items are counted once or twice a year.
- Keys and small kit: NFC key fobs that a phone can tap to check them out.
Common mistakes when choosing RFID tags
- Using a standard label on metal. Metal detunes ordinary UHF antennas, so the tag may not read at all. Use on-metal tags.
- Buying the wrong frequency. A phone reads NFC (HF), not UHF. Bulk counting at a distance needs UHF tags and a UHF reader.
- Skipping a pilot. Test a handful of candidate tags on your real assets, in the positions you plan to use, before ordering in bulk.
- Encoding data on the tag. Writing a department or room into the EPC means the tag is wrong as soon as the asset moves.
- Not recording the TID. Without it, a copied tag looks identical to the original.
RFID tags in Asetavo
Asetavo links each RFID tag to exactly one asset. Commissioning stores the EPC and, where available, the TID, so a cloned or swapped tag can be flagged. Tags can be decommissioned and reassigned when an asset is retired. UHF RFID with handheld and fixed readers is part of the Business plan; NFC tags work from the Growth plan. See RFID asset tracking with your own readers for how reads become audits, zones and alerts.
