What is the size of the smallest NFC tag?
Smallest NFC tag The smallest NFC tag you can buy is the 14mm round NFC Laundry Tag. This disc tag includes the universally compatible Ultralight NFC chip with 46 bytes (approx 46 characters) of usable memory. Specifically design to withstand industrial laundry processes this is a very tough tag. Where a sticker tag is required we also offer the 12x19mm NTAG203 Midas and 19x19mm MiniBlock Ultralight Wet Inlay. Both these clear tags are well suited for a wide range of NFC applications. Where custom print is required we also offer the 19x19mm Standard Delivery Custom Print NFC tag including the NTAG203 NFC chip. The above sizes are the minimum dimensions that still allow for a usable scan distance. Smaller than this and an NFC reader or phone would struggle to scan the tags.
RFID is the process by which items are uniquely identified using radio waves, and NFC is a specialized subset within the family of RFID technology. Specifically, NFC is a branch of High-Frequency (HF) RFID, and both operate at the 13.56 MHz frequency. The Smallest NFC tag can be as small enough to fit between the ridges of human finger prints. That's quite small.
This is not an NFC tag. This is NFC chip. There is a big difference between NFC tag and NFC chip. Tags are much larger because they must also include NFC antenna in the form of printed circuitry or copper wires, so antenna could power up the NFC chip from induced electricity, and could also communicate back to the NFC reader.
Most of the chips used in simple NFC tags are real small, exactly like in this photo. More complex chips are a bit larger, but also quite small. The NFC antenna is the one that cannot be made too small b/c by the law of physics it needs to harvest the induced electricity from the reader and that if you make antenna diameter twice smaller it would harvest 4 times less of induced electricity.
How much power NFC antenna can harvest is in inverse square correlation with antenna's diameter, assuming a round antenna shape, and it would get even worse for irregular (rectangular or stretched) antenna shapes.
All the above makes it quite difficult to produce NFC tags with both good reading distance and small size.