Key takeaways:
- An NFC tag is a passive chip and antenna with no battery, powered by the phone during each read.
- Phones read tags at 4 cm or less, so nobody can scan a tag from across a room.
- NTAG213 stores 144 bytes, enough for a Google review link that needs about 79 bytes.
- NXP rates its NTAG chips for 100,000 rewrites and 10 years of stored data retention.
- Sticker, card and plate formats carry the same chip; only housing, durability and placement really change.
What this guide covers
An NFC tag is a tiny passive chip wired to an antenna that stores a small piece of data, such as a web link, and hands it to a smartphone held within a few centimeters. There is no battery inside: the phone's own field powers the chip for the fraction of a second the read takes.
The confusion starts when you shop for one. Listings mix sticker labels, NFC cards, key fobs, inlays and chip names like NTAG213 or NTAG215, and most of them never say how much data a real link needs. Buy the wrong chip and a vCard will not fit; stick a standard one on a steel register and it will not respond at all.
This guide explains how NFC tags work on iPhone and Android, the five NFC Forum tag types, the memory math for common uses, how to program a tag with a free app, and where the technology falls short.
What are NFC tags?
NFC tags are small, unpowered labels that contain a microchip and a copper or aluminum antenna, built on NFC technology (Near Field Communication), a short range radio frequency standard at 13.56 MHz. An NFC tag stores a URL, a phone number or Wi-Fi details, and any compatible smartphone or NFC enabled mobile device picks it up with a tap.
The chip and antenna together are called an NFC inlay. That inlay is then packaged in whatever form factor suits the job: a paper sticker, a PVC card, a silicone wristband, an epoxy key fob or a rigid acrylic plate. Companies such as NXP, which designs the NTAG chips, and Avery Dennison, which converts them into labels, are major sources of the inlays inside blank tags sold online.
NFC is a subset of RFID. The difference is purpose: RFID is built for machines, NFC is built for phones. A UHF RFID tag in a warehouse is scanned from meters away by a dedicated reader; an NFC tag is meant to be tapped on purpose, by a person.
For a shop or restaurant, that passive chip placed where customers already stand becomes a one-tap shortcut to a web page, which is exactly how an NFC review plate sends people to a Google review form without typing.
How do NFC tags work?
NFC tags work by magnetic induction: the phone's NFC reader emits a 13.56 MHz field, the tag's antenna harvests that energy, and the chip wakes up long enough to send its stored data back. On the tags most people buy, the data exchange runs at 106 kbit/s and takes a fraction of a second.
Near Field Communication (NFC) is a set of short-range wireless technologies, typically requiring a distance of 4 cm or less to initiate a connection.
Android Developers, Google, NFC overview documentationBecause the tag has no power source, it cannot broadcast, track a location or wake a phone by itself. Nothing happens until someone brings an NFC enabled device into range.
What happens on Android
Android phones look for tags whenever the screen is on and the phone is not locked, as long as NFC is switched on in Settings. The system reads the NDEF message (the standard NFC Data Exchange Format), finds the URL and opens the right app, usually the browser.
What happens on iPhone
On iPhone, reading works without any app: Apple's Core NFC documentation states that iPhone XS and later support background tag reading, shown as a notification the user taps. Reading pauses while the camera or Apple Pay is in use. Older models, from iPhone 7 to iPhone X, need an app such as NFC Tools to read a tag. Our guide to iPhone support for tap-to-review cards covers the model list in detail.
What are the types of NFC tags?
NFC tag types are defined by the NFC Forum as Type 1 through Type 5, each based on a different radio standard. For everyday uses like links, contact details and automation, the NXP NTAG21x family dominates the market because it is cheap and works with every phone.
| NFC Forum type | Common chips | Typical use |
|---|---|---|
| Type 1 | Topaz (legacy) | Removed from the 2021 specifications |
| Type 2 | NTAG213, 215, 216, MIFARE Ultralight | Stickers, cards, plates, marketing links |
| Type 3 | Sony FeliCa | Transit and payments, mostly Japan |
| Type 4 | MIFARE DESFire, NTAG 424 DNA | Access control, secure authentication |
| Type 5 | NXP ICODE (ISO/IEC 15693) | Libraries, healthcare, longer read range |
The NFC Forum specifications page notes that Type 1 tag features were removed from its Technical Specification Release 2021, so skip any old stock labeled Topaz. Type 4 tags follow ISO/IEC 14443 and add cryptography, which is why building badges and secure product labels use them.
NTAG213 vs NTAG215 vs NTAG216: how much memory do you need?
The NXP NTAG213, NTAG215 and NTAG216 differ mainly in memory size: 144, 504 and 888 bytes. A link rarely needs more than 100 bytes, so NTAG213 covers most jobs, while contact cards and Wi-Fi credentials with long passwords are the main reasons to move up to NTAG215.
According to NXP's NTAG213/215/216 product specifications, these chips offer 100,000 write cycles and 10 years of data retention.
Write cycles only matter if you rewrite often. Every customer tap is a read, which does not wear the memory, so a tag written once at setup never approaches that ceiling.
The full breakdown of chip lifespan and write limits explains why the housing usually fails long before the electronics. To see what actually fits in each memory size, we encoded three real payloads, counting the NDEF record header, the URI prefix code that compresses "https://" into one byte, and the start and end markers:
| Payload | Bytes on tag | Smallest chip |
|---|---|---|
| Google review link (placeid URL, 79 characters) | 79 bytes | NTAG213 (65 bytes spare) |
| Short g.page review link | 39 bytes | NTAG213 |
| 10-line vCard (name, phone, email, address, site) | 280 bytes | NTAG215 |
The contrarian point: more memory does not mean a better tag. NTAG216 does not read faster or farther than NTAG213, since range depends on antenna size and the phone, not on the chip. If you only store a link, the 888-byte chip is money spent on empty space.
The rule of thumb is simple. Choose NTAG213 for a single link, NTAG215 for a vCard or a Wi-Fi record, and NTAG216 only when you need several records on one tag, such as a link plus a contact file.
A review plate arrives with its NFC chip and QR code linked to your Google review page. Customers tap or scan, the form opens, and there is no monthly fee to keep it running.
See the review plate →
NFC tags vs NFC stickers vs NFC cards
NFC tags, NFC stickers and NFC cards use the same kind of chip; the difference is the housing around the inlay. For business use, the housing matters more than the chip model.
The key features that change from one format to another are durability, visibility and price. The housing decides how long the tag survives, from a few months for a paper sticker in a kitchen to years for a rigid plate.
A thin adhesive label, often 25 to 30 mm round. Cheapest option and easy to hide, but it scuffs, peels and fades in sun or rain.
A credit-card size PVC shell (ISO/IEC 7810). Good for handing out or carrying, and printable on both sides with a QR code backup.
Rigid acrylic, wood or epoxy. Heavy duty and visible, the right choice for a counter, a table or an outdoor wall.
For a fixed collection point, the sticker's low price is often a false saving: it gets knocked, cleaned and ignored. We weighed those plate versus sticker trade-offs for counters in a separate comparison.
How to program NFC tags
To program NFC tags, install a free NFC programming app, add a URL record, hold the phone over the blank tag and press write. Any Android phone with NFC and any iPhone 7 or later on iOS 13 or newer can write a tag in under a minute, with no special hardware or paid software.
- Install NXP TagWriter or NFC Tools; both write NFC tags on iPhone and Android.
- Pick "Write" and add a record: URL, text, phone number, email or Wi-Fi network.
- Paste your link and check the byte count the app shows against the chip memory.
- Hold the top of an iPhone, or the back of most Android phones, flat on the tag until the app confirms.
- Test the tag with a second phone before you stick it anywhere.
- Do: keep programmed NFC tags editable until you have tested them in place for a few days.
- Do: set a password in TagWriter if the tag sits in public and you may edit it later.
- Don't: use "lock" or "make read-only" casually; locking is permanent and cannot be undone.
- Don't: write a long tracking URL when a short one fits a smaller, cheaper chip.
What is an NFC tag used for?
An NFC tag is used to trigger one action from a tap: open a web page, share contact details, connect to Wi-Fi, launch an automation or check in. Businesses use programmed NFC tags for reviews, menus and product information; at home they mostly trigger phone automation.
NFC tags for business
- Google review requests at the counter or on the table, with a QR code for phones without NFC.
- Digital business cards that share a contact file instead of paper.
- Restaurant menus, product manuals and warranty registration on packaging.
- Guest Wi-Fi access in hotels, rentals and offices.
- Access control badges and time tracking, usually with secure Type 4 chips.
NFC tag ideas for home and office
Popular automation ideas use iPhone Shortcuts or Android apps such as Tasker: a tag on the nightstand that silences the phone, one in the car that starts navigation, one by the office door that logs your hours. These tasks run on the phone, and the tag only acts as a physical switch.
A passive tag cannot take payments. Apple Pay, Google Wallet and other payment systems use tokens held in the device's secure hardware, so a cheap programmable NFC sticker will never act as a contactless card.
Why NFC tags fail to read
NFC tags fail to read mostly for physical reasons: metal behind the tag, a thick phone case, the wrong spot on the phone or a cracked antenna. Steel and aluminum surfaces are the usual culprits, because they absorb the reader's field and detune the antenna, so a standard sticker on a fridge goes silent.
The fix is an on-metal NFC tag with a ferrite layer that shields the antenna. Otherwise, move the phone slowly and remove magnetic cases. Heat and bending damage the antenna long before the electronics fail.
Are NFC tags secure?
NFC tags offer enough security for public, non-sensitive data like links, because the 4 cm range makes remote reading impractical and a tag cannot read anything from your phone. The real risk is tampering: someone rewriting an editable tag or sticking a fake one on top.
Password protection and permanent locking prevent rewrites, and NTAG chips carry an originality signature that apps can check. The phone also shows where a link goes before opening it, so check the address as you would for any QR code.
Frequently asked questions
Where can you buy NFC tags?
Blank NFC tags are sold by electronics distributors, specialist RFID stores and large online retailers, usually in packs of 10 to 100 pieces, and some print custom NFC tags with your logo. Check the chip model and the memory before you order, since cheap unbranded listings often skip that information.
Do NFC tags work without internet?
An NFC tag itself needs no internet, Wi-Fi or Bluetooth: the phone reads what is stored on it offline. What happens next depends on the data. A contact file or Wi-Fi record works offline, while a web link, such as a review page, only opens if the phone has a data connection.
Can you reprogram an NFC tag?
You can reprogram an NFC tag as often as you like, within the rated write cycles, as long as it has not been locked. Open your programming app, write the new record over the old one and test it. A tag that was set to read-only keeps its data permanently and cannot be changed.
Where is the NFC reader on my phone?
On an iPhone, the NFC reader sits along the top edge, next to the camera. On most Android phones it sits in the middle of the back, near the camera module, with small differences between Samsung and Pixel models. If a tag does not respond, slide the phone slowly over it until you find the sweet spot.
How do I stop the "NFC tag detected" message?
On Android, the message appears when the phone finds a tag it cannot open, often a bank card in a wallet case. Turn NFC off in Settings, under Connected devices or Connections depending on the brand, or keep cards away from the phone. On iPhone, background reading reacts only to tags holding a supported link.
Choosing your first NFC tag
Start from the job, not the chip. Write down the exact data the tag must carry, count its length, and pick the smallest chip that fits with room to spare. Then choose the housing for the place it will live: a sticker for a notebook, a card for a wallet, a rigid plate for anywhere customers touch it daily. Program one, test it on an iPhone and an Android phone in the real spot for a week, and only then lock it or order more. Which surface in your business do people already reach for with their phone in hand?
