RFID Button - 16mm (125kHz)

This is a simple, thumbnail-size RFID tag. These tags are great for sensing presence, identification, etc., and they're small, so they can be easily sewn into clothing or inserted into enclosures. Each tag comes with a unique 32-bit ID code and is not reprogrammable. The carrier frequency of this tag is 125kHz, so it works great with our ID-2, ID-12 and ID-20 RFID readers.

We tested this RFID tag with one of our ID-12 readers and measured a maximum read distance of about 32mm.

  • 32-bit unique ID - non-reprogrammable
  • 125kHz read frequency
  • EM4001 ISO based RFID IC
  • Manchester encoding
  • Diameter: 16mm
  • Thickness: 1.85mm


RFID Button - 16mm (125kHz) Product Help and Resources

SparkFun RFID Starter Kit Hookup Guide

May 5, 2015

Learn the basics of how to get started with the SparkFun RFID Starter Kit.

SparkFun Qwiic RFID-IDXXLA Hookup Guide

March 14, 2019

The Qwiic RFID ID-XXLA is an I2C solution that pairs with the ID-LA modules: ID-3LA, the ID-12LA, or the ID-20LA, and utilizes 125kHz RFID chips. Let's take a look at the hardware used for this tutorial.


Looking for answers to technical questions?

We welcome your comments and suggestions below. However, if you are looking for solutions to technical questions please see our Technical Assistance page.

  • Member #121090 / about 12 years ago / 1

    I'm trying to build a set of 30 (different ID's) blocks that communicate with another when sat side by side (each block is approx 30mm cube). My idea is to have a sensor in each block so it knows when it is sat beside the other, communicate with each other, and know which blocks are on each side (left and right on table). Then do something. Are there any RFIDs/sensors that will work for this so that I don't have to have a reader at one end of the string of blocks? Thank you!

    • Member #381538 / about 12 years ago / 1

      Hey, I'm working on a similar project. Did you ever figure this out? I'm interested in hearing about your solution.

  • rei_vilo / about 13 years ago / 1

    Do you plan to have a smaller tag?
    1.6mm is just .1mm too big!

    • Pearce / about 13 years ago / 1

      We do have the glass capsule tag which is smaller, have you seen that?

      • rei_vilo / about 13 years ago / 1

        Yes, I did. Thanks.
        But I need a tag I could glued on a 15x15 mm flat surface!
        I'm afraid removing 0.5 mm on the periphery would damage the antenna.

        • SFR75 / about 12 years ago / 1

          hey. did you manage to find smaller tags ? I need even smaller one - 13x13 mm flat... I wonder if inside this tag there is clear disk with plastic border, which you can shave down. have you tried to open it ?

  • joshie / about 13 years ago / 1

    Can someone explain the differences between the 125kHz and the 13.56MHz RFID systems? Why use one over the other? Is one better for tinkering with?

  • Member #73853 / about 13 years ago / 1


    • hobgoblin612 / about 13 years ago / 1

      plastic should be fine as long as the tag is still within range of the reader. aluminum wont work as is blocks the signal.

  • JimHough / about 14 years ago / 1

    What data rate do these transmit at?
    Is it f/16, f/32 or f/64 (f being 125kHz)
    From my research this changes from one tag to another.

  • zsunsun / about 15 years ago / 1

    Is there a way to extend its range little bit? maybe like 2 to 3 meters? I would love to make proximity door opener!

  • thisupend / about 15 years ago / 1

    is there anyway to get a few holes like a real button or do i have to sew a small pocket around it

    • Liencouer / about 15 years ago / 1

      buy a couple, drill some holes, let us know if they work? :D

      • You could also use an epoxy and glue it to a button, though then you couldn't resew it.

Customer Reviews

5 out of 5

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Perfect Size and Works Great!

Small enough to slip in my phone case and read through the rubber backing. Well worth waiting for it to be back in stock!