KGO-DT has an ERP of 561K. It's about the average. Some of the stations are higher powered, some are lower as shown in the list below. Each station is licensed for the power of their transmitter times the gain of their antenna. Everyone in the Bay Area is putting out all they can with the equipment they have.
Larry
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Channel - PSIP Virtual Channel - Effective Radiated Power*
12 - 11.1 - 8.9 KW
19 - 20.1/20.2 - 383 KW
24 - 7.1/7.2 - 561 KW
29 - none - 1000 KW
30 - 9.1/9.2 - 777 KW
45 - none - 206 KW
52 - 36.1/36.2 - 251 KW
56 - 2.1 - 501 KW
57 - 4.1 - 1000 KW
*=From
http://100kwatts.tmi.net/tv/SFO.html
The other stations that aren't on the air are also listed there.