What is bluetoothd on Mac?

What bluetoothd does

bluetoothd (/usr/sbin/bluetoothd, running as root) is the Bluetooth stack. It pairs and connects devices, manages profiles (audio, keyboard and mouse, game controllers), reads battery levels, and handles Bluetooth Low Energy scanning and advertising. LE is what lets your Mac find nearby iPhones for AirDrop and Handoff, unlock with Apple Watch, and take part in Find My.

Audio from Bluetooth headphones is handed to coreaudiod; Continuity features are coordinated with sharingd and rapportd.

Why it uses CPU

• A reconnect loop: a device with a low battery, a bad pairing record, or one that’s just out of range connects and drops every few seconds.
• AirPods switching: automatic switching between your Mac, iPhone and iPad, and the change to the lower-quality headset profile when a mic turns on.
• Busy surroundings: hundreds of advertising devices in an office, conference or train.
• Many devices at once: keyboard, mouse, trackpad, headphones and a controller all connected.
• Interference: USB 3 hubs and some docks emit 2.4 GHz noise, which causes retries.

How to make it calm down

1. Look for a flapping device. This shows connect and disconnect events from the last 10 minutes:

/usr/bin/log show --last 10m --process bluetoothd --style compact | grep -iE 'disconnect|connected' | tail -30

2. Forget and re-pair the device that keeps showing up: System Settings › Bluetooth, click ⓘ next to it, Forget This Device.
3. Charge or replace the battery in old keyboards and mice.
4. Restart the daemon:

sudo pkill bluetoothd

5. Move USB hubs and SSDs away from the Mac’s Bluetooth antenna (on MacBooks it’s near the hinge).
6. List what’s paired and connected:

system_profiler SPBluetoothDataType

When to worry

The real binary is in /usr/sbin:

codesign -dv --verbose=2 /usr/sbin/bluetoothd 2>&1 | grep -E 'Identifier|Authority'

Be wary of paired devices you don’t recognize, especially keyboards: a paired keyboard can type on your Mac. Remove any unknown entries in Bluetooth settings.

Seeing it in Stat Space

Stat Space’s Devices tab shows every Bluetooth device with battery levels (including AirPods left, right and case) and signal strength, lets you connect or disconnect, and keeps a Recent list of connects and disconnects. A device that appears there ten times in an hour is the one keeping bluetoothd busy.