125KHz vs 13.56MHz RFID Keyfobs and Cards: What to Buy
By Official Hobby Components Online Store | Buy Electronic Kits, Components, Boards, Shields, Modules | Published: 2026-10-31
Category: Buying Guides
Pick the right RFID tag for your reader: 125KHz ID fobs and cards for simple access control, or 13.56MHz IC keyfobs for ISO14443A and Mifare projects. Compare compatibility, cost, and use cases.
Quick answer
For simple, low-cost access control or projects using the RDM6300 reader, choose 125KHz ID keyfobs or cards. For ISO14443A or Mifare-compatible systems, choose 13.56MHz IC keyfobs. Match the tag frequency to your reader first; then decide between a keyfob and a card based on how users will carry it.
Frequency is the compatibility rule that matters most
A 125KHz reader will not read a 13.56MHz tag, and a 13.56MHz reader will not read a 125KHz tag. The RDM6300 module is designed for 125KHz read-only tags and read/write cards, so it pairs with the 125KHz keyfobs and cards. The 13.56MHz IC keyfobs are built for ISO14443A and NXP Mifare systems, so they need a reader that supports that standard. Check your reader's datasheet or product page before buying tags in bulk.
Keyfob vs card: carrying method and durability
Keyfobs attach to a keyring, which suits staff or household members who already carry keys. Cards fit a wallet or badge holder and are easier to print or label for visitors. The 125KHz keyfobs here are made from hard-wearing ABS plastic, while the 125KHz cards are approximately 55x86x0.8mm and have the unique ID printed on the back. Neither option is inherently more secure; both are read-only ID tags with a fixed unique number.
What you give up with low-cost ID tags
These 125KHz and 13.56MHz tags are pre-programmed with a unique ID and require no programming to use. That makes them simple and inexpensive, but it also means you cannot rewrite the ID or store custom data on them. If your project needs read/write capability or cryptographic security, look for a different tag type that explicitly supports those features. The catalog does not list read/write or encryption specifications for these products, so treat them as fixed-ID tags.
Decision rules for buying RFID tags
- Start with your reader: If you own or plan to buy an RDM6300 or another 125KHz reader, buy 125KHz tags only. If your reader supports ISO14443A or Mifare at 13.56MHz, buy 13.56MHz tags only. Never mix frequencies on the same reader. Write down your reader's frequency before adding tags to a cart.
- Choose keyfob or card by carrier: Pick keyfobs for people who carry keys daily and want a tag that attaches to a keyring. Pick cards for wallet carry, badge holders, or visitor passes where a flat card is easier to label and hand out. Order a small mixed batch first if you are unsure which form factor users will accept.
- Match quantity to enrollment: The 13.56MHz keyfobs come as a set of 10, the 125KHz keyfobs as a pack of 5, and the 125KHz cards as a set of 10. Count your users plus spares before ordering, and remember that lost tags usually need replacement rather than reprogramming. Keep at least one spare tag per 10 users to avoid lockouts.
- Accept fixed-ID limits or upgrade: These tags are pre-programmed with a unique ID and need no programming. If your project requires changing the ID, storing data, or encryption, these fixed-ID tags are the wrong choice; look for a tag that explicitly supports read/write or secure features. Confirm read/write or security needs before buying fixed-ID tags in bulk.
Product facts to know
- 13.56MHz RFID (IC) Keyfob (Set of 10): 13.56MHz RFID keyfobs compatible with ISO14443A and NXP Mifare, supplied as a set of 10. Choose these only if your reader explicitly supports 13.56MHz Mifare or ISO14443A; they will not work with the 125KHz RDM6300.
13.56MHz RFID (IC) Keyfob (Set of 10) - 125KHz RFID (ID) Keyfob: 125KHz RFID keyfobs with a unique serial number, no programming required, in a pack of 5. These are a direct match for the RDM6300 reader and the RFID door access system, making them a low-cost starting point for simple access projects.
125KHz RFID (ID) Keyfob - 125KHz RFID (ID) Card (Set of 10): 125KHz RFID cards, set of 10, each pre-programmed with a unique ID printed on the back, approximately 55x86x0.8mm. The printed ID lets you record which card belongs to which user without a reader, which simplifies enrollment and auditing.
- RDM6300 125KHz (ID) RFID reader module: RDM6300 125KHz reader module designed for 125KHz read-only tags and read/write cards. This module sets the frequency for your whole system: buy 125KHz tags if you standardize on it, or choose a different reader for 13.56MHz tags.
Who should buy which
Best for
- Hobbyists building a simple 125KHz access system with the RDM6300 reader
- Small offices or households needing low-cost ID keyfobs or cards for door access
- Makers who want pre-programmed tags with no encoding step
Not for
- Projects using 13.56MHz Mifare or ISO14443A readers (choose the 13.56MHz keyfobs instead)
- Applications that require rewriting tag data or storing custom payloads
- Security systems that depend on cryptographic authentication rather than a fixed ID
