The drawbacks of NFC technology

A seller who only says good things about their own technology teaches customers to distrust them. So here is what NFC does badly, in the order it happens, and what can be corrected.

Metal, the only truly physical limit

An NFC chip has no battery. The phone powers it through a very short-range magnetic field. Put that field against a metal surface and it collapses: metal absorbs the energy before it reaches the antenna.

A stainless steel counter, a till, a payment terminal, a worktop with a metal frame — all produce the same effect. The plate stops responding, and the owner concludes it is faulty.

Two corrections exist, and only one is good. Moving the support a few centimetres away often works, but shifts the problem: where the plate works is not always where the customer sees it. A ferrite layer between the chip and the support isolates the field from the metal and leaves the placement free. That is what our anti-metal plate does, and its own guide explains how.

This is the one NFC limit that no software setting works around. It is solved at manufacture.

Phones that cannot read

On Android, NFC has been standard on devices sold since 2016, but it is still missing from part of the entry-level range: it is one of the first components dropped to hit a price. On Apple, tag reading exists from the iPhone 7 running iOS 11; earlier models sometimes carry a chip, but it is reserved for payment and will never read a plate.

Then there is the most common case, and the most annoying: a perfectly compatible phone whose NFC is simply switched off in the settings. Our guide on phone compatibility explains how to check in ten seconds.

None of this can be fixed by the business owner. The only answer is not to depend on NFC alone: a QR code printed on the same support opens the same page, with no chip and no setting. That is why our plates carry both, at no extra cost.

What we measure on our own supports confirms it: 71% of openings go through NFC, 29% through the QR code. In other words, nearly one customer in three could have done nothing with an NFC-only plate.

The gesture nobody was taught

This is the least technical limit and the most expensive one. Holding a phone near an object to open a page is not an acquired reflex, except among those who pay contactless — and even then, they associate the gesture with payment, not with opening a link.

The symptom is recognisable: the plate is in place, it works, and nobody uses it. Three causes, in this order of frequency.

• The support is out of sight at the moment the phone is in hand. The useful moment is payment, not arrival.
• The NFC pictogram stands alone. It only speaks to those who already know. "Hold your phone near" does the work the logo does not.
• Nobody mentions it. One sentence from the team while handing back change moves the numbers more than the placement does.

Three limits wrongly attributed to NFC

Short range. A few centimetres, and that is a safeguard rather than a flaw: it stops a plate from firing as someone walks past without meaning to.

The customer's battery. Reading takes less than a second and does not register over a day of use. Leaving NFC on permanently costs nothing.

Lifespan. With no battery and no moving part, the chip does not wear out from being read. What fails is its casing — covered in our guide on how long an NFC chip lasts.

What about security?

The real risk is not remote reading, which is impossible at this range. It is rewriting: a chip left unlocked can be reprogrammed by anyone who holds a phone near it, using an ordinary app. The customer then scans your plate and lands somewhere else, without you knowing.

The fix is permanent and done once: lock the chip against writing after programming. We do this as a matter of course, and the guide on locked chips sets out exactly what it prevents.

One objection follows: if the chip is locked, how do you change the destination? Because the chip does not hold your destination, but an intermediate address. See changing the link on an NFC plate.

What to check before buying

Three questions are enough to rule out supports that ignore these limits.

• Does a QR code come with the chip? Without it, you lose nearly one customer in three.
• Is the chip write-locked? If the seller cannot answer, it is not.
• Will the support sit on metal? If so, you need a ferrite layer, not good intentions.

None of these limits is a deal-breaker. Staying quiet about them, on the other hand, leaves the owner to discover them alone, once the plate is already on the counter.