How Does a Bluetooth FM Transmitter Work? (Things to Know)

If your car doesn’t have built-in Bluetooth technology or an auxiliary port, the perfect solution to enjoy music on the ride is a Bluetooth FM transmitter.

What is a Bluetooth FM transmitter? How does a Bluetooth FM transmitter work? When you plug the device into your car, its screen will display a radio frequency. All you need to do is connect your phone with the device via Bluetooth, tune your radio into that frequency, and stream your favorite music directly from your phone to your car stereo.

An FM transmitter also opens different ways to listen to music in your car. Explore your options below!

Who Needs a Bluetooth FM Transmitter?

Nowadays, there is built-in Bluetooth in all cars. The technology allows you to play your favorite music or podcasts from your phone to the car stereo. It is convenient and free of charge so many people prefer it over CDs or paid radio services.

However, older cars might not come with built-in Bluetooth. The owners can only use CDs or FM radio. The cost to install a built-in Bluetooth head unit is up to $500. That is when you need a Bluetooth FM transmitter. When you plug it into your car, it will act as a Bluetooth receiver. The best part is the device only costs $20.

How Does It Work?

What is an FM transmitter used for? A Bluetooth FM transmitter is similar to a Bluetooth receiver, but instead of sending the audio from your phone to your car via Bluetooth, it broadcasts the music on an open FM transmitter frequency.

When you plug an FM transmitter into your car, its screen will display a frequency. You need to connect your phone with the device via Bluetooth and tune your car radio to this frequency to start streaming.

In terms of tchnical details, a wireless Bluetooth FM transmitter works through radio waves. The Bluetooth technology converts the music on your phone into radio waves and sends them out on a radio frequency.

When you tune to the correct channel, the FM transmitter catches the radio waves. Then, it vibrates the radio speaker at the same amplitude as the signals received, generating the music you hear.

Benefits and Drawbacks of Wireless FM Transmitters



  • Simplicity

An FM transmitter is small and easy to use. You only need to plug it into your car to activate; no wiring is required.

Besides in-car FM transmitters, you will find dual-frequency FM transmitter models that provide wider transmission distances. You can use them to stream audio for meetings, home stereo systems, or even broadcast your own radio station.

  • Built-in USB ports

Bluetooth FM transmitters often come with one to two built-in USB ports and an SD card slot. You can use them to charge your phone, listen to music from a USB or an SD card.

  • Info display

Wireless transmitters’ displays show you information about phone calls, FM channels, music, or even car battery voltage.

  • Hand-free calls

Looking at your phone while driving is dangerous. With a Bluetooth FM transmitter, you can answer, reject, hang up, or re-call with the click of one button.


As the device transmits on an FM frequency, the sound quality it delivers is equal to that of an FM radio, which is lower than CD quality. The Bluetooth signals can also interfere with other radio signals and cause static noise.

So, while wireless FM transmitters are convenient, they might bring sound interference, especially in crowded areas.

But don’t worry! Many modern wireless models have noise-cancellation technology that dampens background noises, providing clearer and crisper sound.

How to Use a Bluetooth FM Transmitter


Setting up an FM transmitter is simple. Follow these steps:

  • Step 1. Plug the device into your car cigarette lighter socket.
  • Step 2. Turn on your phone’s Bluetooth and find the device in the Bluetooth setting.
  • Step 3. Connect your phone to the device.
  • Step 4. On the transmitter’s screen, you will see an FM frequency. Tune your car radio to that frequency.
  • Step 5. Now you can stream music directly from your phone to your car stereo.

You can play and pause tracks from your phone or directly on the transmitter. Also, you can listen to anything available on your phone, including songs in the music library, podcasts, phone calls, and map directions.

Check out this video:


Does an FM transmitter work without a radio?

Unfortunately, it doesn’t. If you can’t tune a radio to the correct frequency, the transmitter won’t pick up the signals from your phone. It only works when your car has a radio.

Will a Bluetooth FM transmitter work in old cars?

Yes, the device does work in old cars, as long as your car has a cigarette lighter socket and an FM radio.

Will a Bluetooth FM transmitter drain my car battery?

Bluetooth FM transmitters consume minimal energy, so they won’t drain your car’s battery. Also, it will turn off when you switch off your car’s engine. So, you can leave your transmitter plugged in at all times without worrying about the battery.


To wrap up, a Bluetooth FM transmitter helps stream music from your phone to your car’s radio. It is helpful for cars that don’t have a Bluetooth head unit.

When you know the answer to “how does a Bluetooth FM transmitter work” it’s easy to pick the device that suits you most. So, don’t hesitate to share this article with your friends. You might help someone in need.

If you have any further questions, let us know in the comment section. Thank you for reading!

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