There are three basic types of Bluetooth radio range: Class 1, Class 2, and Class 3.
Here are the maximum and expected/average ranges for each class:
- Class 3: 1 meter / 3.2 feet maximum; about 0.5 meter / 1.6 feet average
- Class 2: 10 meters / 33 feet maximum; about 2-5 meters / 6.5-16 feet average
- Class 1: 100 meters / 328 feet maximum; about 20-50 meters / 65-160 feet average
You'll never see the maximum figures in the real world, because:
- The materials in the casing of your headphones and your computer are a barrier between the antenna and the outside world, which attenuates (degrades) the signal slightly before it even leaves the device.
- The maximum range of Bluetooth is (I believe) tested in a vacuum, not in air. The molecules in air slightly attenuate the signal, though this only really makes any difference for Class 1 distances.
- There are other wireless signals from many different devices that transmit in the same spectrum (2.4 GHz) as Bluetooth. Some of these signals are data, like WiFi signals; others are "noise" that simply make it harder for everyone to use the spectrum, like small amounts of microwave radiation that leak from microwave ovens (also 2.4 GHz).
As a result, depending on how polluted your environment is with 2.4 GHz signals, you might only get 10% of the advertised range, or even less if you try to put another barrier (like a wall, or a monitor) between the two Bluetooth devices.
Recent Bluetooth chipsets in laptops, desktops and smartphones nowadays are starting to be Class 1, but it wasn't long ago when they were all Class 2. I haven't seen Class 3 transmitters in anything that does Bluetooth audio, but I wouldn't be surprised if there were some on the market.
One thing to keep in mind is that, in order to get a higher class range (like Class 1), both your transmitter and your headphones must be capable of transmitting in that class, or your range will be limited to the lowest-class device you have. Bluetooth is a "bidirectional" protocol, meaning that your headphones also send data back to your audio transmitting device.
If your headphones can "hear" the audio data signal from your transmitting device just fine, but your headphones are of a lower transmitting class and can't send the response data back at a high enough gain for the source device to receive it reliably, you'll get dropouts.
To get an idea of what it's like to have a Class 1 Bluetooth setup, consider mine:
- My desktop computer has an Intel 8265 Class 1 Bluetooth radio, with two adjustable antennas on the back of the system.
- My Macbook Pro and iPhone both have Class 1 Bluetooth radios.
- My Beats Solo3 Wireless headphones have a Class 1 Bluetooth radio.
With my desktop, laptop or phone and the headphones above, not only can I leave the room with my headphones, but I can walk across the hall, into another room (through two walls), and still get a reliable signal with no dropouts. The entire floor of my house is within range of my Bluetooth headphones (about 55-60 feet), even with walls in between my transmitter and headphones.
In noisy wireless environments, like in a densely populated city street, Class 2 devices often have a range as low as 2 feet, and will drop out if you put your phone in your pocket. With a Class 1 setup, you can comfortably listen to audio with no dropouts on your smartphone or laptop while holding it or wearing it somewhere on your person, even in areas with some of the most crowded wireless spectrum.
Because WiFi devices share spectrum with Bluetooth, your Bluetooth range experience will tend to be very different if you live in a densely packed apartment in a city, vs. living out in the country or suburbs. In cities you might have 50 or 100 2.4 GHz wireless base stations within range; in less populated environments the number would be much less. You can probably at least walk around your bedroom with no problem with Class 1 even in a city, though.