Your phone's Bluetooth is broadcasting more than you think — here's how to limit it

I treat Bluetooth like a light switch. I turn it off when I don't need it, and assume it's gone.

You did too, right?

Turns out, we're wrong. When you're not actively connected to anything, your phone is still talking, constantly, to anyone nearby set up to listen.

Your Bluetooth signal isn't really turned off. Instead, it's advertising your smartphone, broadcasting identifiers, and in some cases, actually connecting to tracking systems you've definitely never agreed to be tracked by.

Bluetooth is doing much more in the background than you think

Connection and broadcasting are different

I think most are familiar with the concept of a Bluetooth connection. You enable Bluetooth on your two devices, hit pairing mode, and make a connection. It doesn't always work seamlessly, but for the most part, Bluetooth is super simple to use and does the job.

The only issue is that Bluetooth is often broadcasting more than you realize when you're not connected to a device — and at times, even when you've hit the Bluetooth toggle on your device.

That's because when you disconnect your smartphone and your headphones, Bluetooth doesn't just "stop." It keeps broadcasting small packets of data containing the device Bluetooth name, a MAC address for unique device identification, Bluetooth profiles supported by your device, and, in some cases, phone specs and more.

None of this requires any permission or interaction on your end. This is actually how Bluetooth works, and the advertising signal is what makes Bluetooth so useful. It's why quick pairing works with headphones, your car stereo, and your fitness tracker, and how it all works without opening an app.

Most of this passive broadcasting is handled by Bluetooth Low Energy — BLE for short. BLE is just the low-power variant of standard Bluetooth, and for most purposes, the distinction doesn't matter much. Both broadcast, both can be tracked. BLE simply happens to be the mechanism doing most of the background work on modern phones, because it's designed to run continuously without significant battery drain.

It really is broadcasting all the time

Note that continuously really means continuously. It never stops. A 2022 UC San Diego research paper isolated a series of devices in controlled environments and measured how frequently they transmitted BLE advertisements with their screens off — the equivalent of a phone sitting in your pocket.

The study found that an iPhone 10 broadcast 872 times per minute, a MacBook Pro broadcast 576 times, and a Google Pixel 5 broadcast 510 times.

It's a constant stream of your device shouting about your device to other Bluetooth devices in the local area.

The same study was originally motivated by COVID-19 contact tracing apps, which pushed BLE beaconing onto hundreds of millions of phones globally. Devices that were already beaconing constantly now had an additional, explicitly always-on BLE broadcast running.

The pandemic essentially normalised the condition the researchers were studying: your phone as a perpetual, high-frequency radio transmitter. Contact tracing apps are largely gone now, but the beaconing behaviour they relied on never was — it was already there, and it remains.

My phone is shouting... but who is listening?

And why?

The answer is way more than you expect, and for a wide variety of reasons.

Retailers and venues have used Bluetooth beacons for years to log when you pass through certain areas, building an idea of footfall, dwell time, and movement patterns. This data is used to tie into loyalty apps, deals, aggregation, and more.

Similarly, ad networks can use Bluetooth signals as an identification tool, and it is particularly useful when combined with Wi-Fi data. It helps anyone tracking you to build more specific reference points across physical locations.

Then there is the chance someone is just running a Bluetooth scanning tool in a public place. If your Bluetooth is broadcasting, they can pick up the signal. Heck, I'm sure you've tried to connect to a new device in a busy location and found it nigh impossible due to all the devices and all the signals — this is exactly what we're talking about.

Your phone is conspiring to keep you broadcasting Bluetooth

Turning it off doesn't turn it off

Here's the thing: turning your Bluetooth off doesn't always do what you think it does.

iOS

On iOS, hitting the Bluetooth button in the Control Center doesn't actually disable the Bluetooth radio. It disconnects your active connections and stops any new Bluetooth pairings, but explicitly keeps Bluetooth Low Energy (BLE) running.

On the face of it, that sounds bad. However, it's a little more nuanced, as BLE is needed to keep features like Find My, AirDrop, Handoff, and other location services working.

So, on iOS, you'll need to head to Settings > Bluetooth and turn it off from there. The iOS Control Center toggle is a shortcut, but not the actual kill switch. Alternatively, you could enable Airplane Mode, but that also has the downside of stopping any other communication.

On iOS, apps must declare Bluetooth usage in their privacy manifest and request permission explicitly. But background Bluetooth access is where it gets murkier — an app with background permission can continue scanning while you're not using it, which is legitimate for fitness apps with wearable integrations and a potential vector for less obvious data collection everywhere else.

Android

It's a similar situation with Android devices, though it's a little more fragmented due to Android's structure. Toggling the Bluetooth switch off stops apps and services from creating new connections, but certain apps holding the Bluetooth Scan permission can continue to scan for BLE devices.

This is for the same reason as iOS: keeping you connected to local health devices, tracking devices, and so on.

However, Android has another quirk. Google's own location accuracy system — which uses BLE beacons to supplement GPS — can continue running background scans even when the toggle is off, reporting nearby beacon identifiers back to Google, unless you explicitly disable it under Location settings; it's "essentially a matter of luck."

But even then, some Android permissions can allow Bluetooth scanning even with Location permissions disabled. As the San Diego researchers put it, the only real way to turn Bluetooth off on your Android device is to turn the whole thing off entirely.

There are more quirks to the system, too. For example, the "Nearby devices" permission group governs Bluetooth access. It sounds like it's purely about pairing, but it also covers scanning, which means an app with nearby devices permission can detect what BLE beacons and other devices are around you. Some apps use this for analytics, A/B testing based on location context, or feeding data to ad networks.

How to stop Bluetooth scanning and broadcasting fully

Lock it down

There are a few ways you can vastly reduce the amount of Bluetooth broadcasts your device makes, but it's not as simple as I'd like. Really, you'd think hitting the Bluetooth icon would do the job, but as we've seen, Bluetooth broadcasting and scanning on smartphones is multifaceted.

The first step is to audit your apps on Android and iOS. Make sure none of them have Bluetooth access unnecessarily. iOS is fairly privacy-focused and doesn't tend to allow excessive permissions to begin with, and in fairness to Android, it's much better than it was even a few short years ago.

• Android: Head to Settings > Privacy > Permission Manager > Nearby Devices.
• iOS: Head to Settings > Privacy & Security, then check the permissions for individual apps.

As mentioned above, on iOS, you can also disable Bluetooth entirely when you're not using it by heading to Settings > Bluetooth and disabling the radio from there. Note that this will stop those previously mentioned features from working.

Android owners can similarly disable Bluetooth broadcasting by turning the Bluetooth scanning feature off. The location of this setting varies between Android devices, so the best option is to open Settings and search for the feature.

Bluetooth is amazing, but this is one of its downsides

I'm not anti-Bluetooth. Far from it. I use it all the time across all of my devices; I never travel without a set of Bluetooth earbuds. On that, if you use wireless earbuds, a smartwatch, or Bluetooth in your car, switching it off completely isn't practical, but it doesn't need to be.

The point is to stop treating the toggle as a guarantee.