1 Acre = 43 560 Square Feet Lot Size: 3,600 Sq. price per acre = 43 560 / 3600 *$1.2m = $14.5m Median San Francisco household income, 2015: $75,910 http://www.sfhip.org/index.php?module=DemographicData&type=user For median income family years to work(without consuming anything) to own one acre of the land $14. 5m / $75,910 = 190 years.