Operational and mission efficiency were estimated for Air Force fighters, bombers and transports from fuel use data from 2001 through 2008 as reported in the Air Force Total Cost of Ownership (AFTOC) database. This analysis estimated efficiency in terms of the best performance theoretically possible for each platform based upon the energy available in the fuel expended. Operational efficiency considered aircraft operations in general, without regard for the type of mission. Mission efficiency only considered use of allocated fuel for combat (non-training) sorties. The cost associated with fuel inefficiency of the combined fighter, bomber and tanker force were estimated based on the fiscal year 2008 costs of fuel, fully burdened to include the cost of aerial refueling. The total cost of operational inefficiency was estimated at $5 billion per year. The fully burdened cost of mission inefficiency added an additional $3.6 billion for a total per year cost estimate of $8.6 billion. This represents 21.5% of the $40 billion portion of the 2009 budget dedicated to modernization. A business case for force-structure change is presented, which describes how these cost savings can be leveraged for modernization. Published by Elsevier Ltd.