- the specific 802.11 protocol employed
- the overall strength of the device transmitter
- the nature of obstructions and interference in the surrounding area
Another rule of thumb holds that the effective range of 802.11a is approximately one-third that of 802.11b/g.
Both of these rough estimates fall on the high end of the range seen in practice. Obstructions in home such as brick walls and metal frames or siding greatly can reduce the range of a Wi-Fi LAN by 25% or more. Because 802.11a employs a higher signalling frequency than 802.11b/g, 802.11a is most susceptible to obstructions. Interference from microwave ovens and other equipment also affects range. 802.11b and 802.11g are both susceptible to these.
Of course, it's possible to extend a Wi-Fi LAN to much longer distances by chaining together multiple wireless access points or routers.