The Agricultural Resource Management Survey of corn growers for the year 2005 and the 2008 survey of dry mill ethanol plants are used to estimate the net energy balance of corn ethanol. This report measures all conventional fossil fuel energy used in the production of 1 gallon of corn ethanol. The ratio is about 2.3 BTU of ethanol for 1 BTU of energy inputs, when a portion of total energy input is allocated to byproduct and fossil fuel is used for processing energy. The ratio is somewhat higher for some firms that are partially substituting biomass energy in processing energy.