What Is an RFID Access Card? 125 kHz vs 13.56 MHz and MIFARE
An RFID access card is a contactless card containing a chip and a small antenna that passes its number or data to a reader by radio. Two families dominate access control: 125 kHz (low-frequency) cards, which often carry nothing but a fixed number, and 13.56 MHz (high-frequency) cards such as the MIFARE family, some generations of which include memory and encryption.
Ask a supplier “which card should I buy?” and you’ll usually hear “125 kHz”, “MIFARE” or “13.56”, with nobody explaining what actually separates them. This article is a general guide for building managers, security leads and purchasing teams: what an RFID card is made of, how the frequencies differ, read-only versus encrypted cards, and whether to choose a card, a key fob or a sticker tag. The technical information here is general; always check any card’s compatibility with your own reader and access control software.
What is an RFID card and how does it work?
RFID stands for radio-frequency identification. Inside every card is a fine coil acting as an antenna and a tiny chip. Most access cards are “passive”: they have no battery, and when held near a reader they draw the energy they need to respond from the reader’s own field. That is why a card’s lifespan depends on physical wear, not on a charge.
What the card hands over to the reader depends on its type. In the simplest case it’s just a serial number written to the chip at the factory. More advanced cards add writable memory protected by cryptographic keys, and the reader must prove its identity before it can read that memory.
125 kHz proximity cards: simple, cheap and widespread
Low-frequency (LF) cards have been used in buildings and car parks for years. Many carry a single fixed number that can’t be changed and is sent every time without any security handshake. Their advantages are a lower price, easy availability and compatibility with lots of existing readers.
Their main limitation is that same simplicity: because the number is sent unencrypted, reading and duplicating it is easier with tools available on the market. That doesn’t make them useless. For doors of ordinary sensitivity, where cards are managed carefully, they’re still a reasonable choice.
13.56 MHz vs MIFARE: what is the difference?
13.56 MHz is the name of a frequency band, not a particular card. Cards in this band (HF) usually have more memory and can store data in separate sectors under different keys. MIFARE is the brand name of a well-known family of cards in this band, and within that family there are several generations and models.
What buyers often miss is that not all 13.56 MHz cards are equally secure. Security researchers have published findings about weak encryption in some older generations of cards in this band, while newer generations are designed with stronger mechanisms. On top of that, many systems read only the serial number from a 13.56 MHz card and never use its encryption; in that case you end up with security much like a simple low-frequency card.
Low-frequency vs high-frequency RFID cards at a glance
| Feature | 125 kHz (LF) | 13.56 MHz (HF) |
|---|---|---|
| Typical data | A fixed number | A number plus sectored memory in many models |
| Encryption | None in most common models | Depends on generation and model, from weak to strong |
| Read range in access control | Short, a few centimetres | Short, a few centimetres |
| Cloning risk | Higher | High to low, depending on model and how it’s read |
| Card cost | Usually lower | Usually higher, especially secure models |
Distances are approximate and depend on the reader, antenna size and installation. Vehicle entrances need a longer range and usually use dedicated tags, which our parking tag guide covers.
Read-only or encrypted access cards?
This is the most important security decision when choosing cards. A read-only card is like a number sticker: anyone with a suitable reader can see the number. An encrypted card is more like a two-way conversation; card and reader recognise each other using a shared key before exchanging data, and anyone without the key gets nothing of value.
But encryption only helps if the whole chain supports it: card, reader, controller and the initial configuration. Buying more expensive cards without the right readers and setup only raises the cost. So before ordering, ask exactly what the system reads from the card.
How serious is RFID card cloning?
In ordinary settings, most security incidents don’t come from cloned cards; they come from cards that were lent out, lost and not reported, or belonging to someone who left but are still active. Even so, at sensitive sites the risk of duplicating simple cards should be taken seriously. The usual three layers of defence:
- Technology: for sensitive doors, use cards with strong encryption that the system actually uses.
- Software: a duplicate card warning, quick deactivation and limits on permitted doors and hours shrink the damage a cloned card can do.
- Procedure: cards issued against a receipt, losses reported immediately and cards collected when someone leaves.
The full lost-card procedure is in a separate article: lost access cards and card cloning.
Card, key fob or sticker tag: which RFID format?
The same RFID technology can come in different forms. The right one depends on how it will be used:
| Format | Advantage | Best for |
|---|---|---|
| Credit-card-sized card | Room for a photo and name, fits a lanyard | Office staff and factory personnel |
| Key fob | Durable, always on the keyring | Residents of apartment complexes, pedestrian doors |
| Sticker or windscreen tag | Stays on the vehicle and isn’t passed around | Car park entrances and company vehicles |
| Wristband | Resistant to water and knocks | Gyms and certain workshop environments |
Many managers combine formats, for example a key fob for the lobby door and a tag for the car for each resident. In that case, it matters that the software can link several cards to one person.
Checklist for choosing access control cards
- Confirm the frequency of your existing or proposed readers; cards must match it.
- Ask whether the system reads only the serial number or uses encrypted memory.
- Classify doors by sensitivity; not every door needs the most secure card.
- Choose the credential format by user: card, key fob or vehicle tag.
- Decide whether you need a photo and details printed on the card.
- Set the number of spare cards and the replacement procedure in advance.
- Get a sample and test it on a real reader before placing a bulk order.
For broader buying criteria, from software to after-sales service, see the card access control buying guide.
What does access control software do with your cards?
However secure a card is, it loses its value without proper management in the software. Nooradio, P-Soft’s access control software, works only with smart cards and tags via the card readers at each gate. You register each person with all their cards in one form, activate or deactivate any card instantly without deleting its history, and get a warning when a duplicate card is entered. From the Pro plan upwards, you can also add a range of cards in bulk and group them, which speeds things up when handing out dozens of cards to staff or residents. The software interface is in Persian.
We make no blanket claims about which card or tag type and frequency will work with your readers; check your reader specifications with P-Soft’s experts before buying cards. And to be clear, Nooradio is not a plate reader, camera system or attendance system.
Frequently Asked Questions
What is an RFID card?
A contactless card with a chip and antenna that sends its number or data to a reader by radio, usually without a battery.
What is the difference between 125 kHz and 13.56 MHz cards?
125 kHz cards often carry only a fixed number; many 13.56 MHz cards have more memory and support encryption.
What is a MIFARE card?
MIFARE is a well-known family of 13.56 MHz cards, with several generations offering different levels of security.
Is a more expensive card always more secure?
Not necessarily. If the system only reads the card’s serial number, its encryption is never used.
Which cards work with Nooradio?
Nooradio works with smart cards and tags through the readers at each gate. Check your specific readers and cards with P-Soft’s experts for compatibility.
To see how your organisation’s cards and tags would be managed in Nooradio, request a demo on the access control software page.
Further reading
- Vehicle Access Control Software: Card & Tag Guide and Use Cases
- Vehicle Access Control: LPR vs RFID vs Remote, Which to Choose?
- Benefits of Parking Management and Vehicle Access Control Software
Complete guide: access control system
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