What is Bluetooth Class?

In Bluetooth, "class" refers to the three levels of power for Bluetooth devices: Class 1, 2, and 3. The following table compares power and range of these three classes:

BT Class >Maximum Power Operating Range
Class 1 100 mW (20 dBm) 100 meters
Class 2 2.5 mW (4 dBm) 10 meters
Class 3 1 mW (0 dBm) 1 meter

To communicate over the 100 meter range, a class 1 BT device is required at both ends. To communicate over the 10 meter range, a class 1 or class 2 device is required at both ends.

Note: Class 3 devices are uncommon due to their very limited range.

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