Bluetooth Power Classes

A question that I frequently hear people asking when it comes to purchasing a Bluetooth product is "do I need Bluetooth Class 1 or Class 2?". In this this post I will describe the different Bluetooth power classes and what class you should select when you next purchase a Bluetooth product.

For a start, I should make it clear that Bluetooth class 1, class 2 and class 3 all refer to Bluetooth power classes, not to be confused with Bluetooth device classes.

The following table compares the available Bluetooth power classes:

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

The actual range for each power class may vary depending upon environmental factors where the Bluetooth device is used. Class 3 devices have a very limited range and not very common, hence, they will be ignored for the rest of this discussion

So which power class should you choose for your new Bluetooth product? The two most important question that should be asked here are: "over what distance do I need my Bluetooth devices to operate?" and "what is the power class of the other Bluetooth device I want to communicate with?" Here are the two important pieces of information that you need to understand:

• If you wish to communicate over the 100m range, you will need a class 1 Bluetooth device at both ends.
  
• If you wish to communicate over the 10m range, you can have a class 1 or class 2 device at both ends.
  

Many people make the mistake of believing that they can extend the range of their class 2 device to 100m by purchasing a class 1 device for the other end. This is simply not true. Consider two people standing 100m apart, if person A yells loud enough for their voice to travel over 100m, person B will be able to hear what person A is saying, but if when person B replies they only yell loud enough for their voice to travel over 10m, person A will obviously not hear the response.

Hopefully this post has cleared up any confusion regarding Bluetooth power classes.