specific fuel consumption

Also known as: SFC

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July 14, 2026

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Specific fuel consumption (SFC) is a measure of an engine's efficiency, indicating how much fuel it consumes per unit of power generated. For jet engines, SFC is a critical performance metric, influenced by factors such as the engine's design, flight speed, and ambient temperature. The ideal thermodynamic efficiency of converting fuel combustion heat into gas horsepower is limited by practical constraints, including peak gas temperature and pressure within the engine cycle.12

In practice, the actual SFC is higher than the theoretical minimum due to inefficiencies in the engine's components. For jet engines, the overall efficiency is assessed by measuring fuel consumption per unit of thrust generated. This value is not only dependent on the prime mover's efficiency but also on the propulsor's efficiency and the aircraft's flight conditions.21

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jet engine
The prime mover
…of specific fuel consumption (SFC) for an engine producing gas horsepower is 0.336 (pound per hour)/horsepower, or 0.207 (kg per hour)/kilowatt. In actual practice, the SFC is even higher than this lower limit because of inefficiencies, losses, and leakages in the individual components of the prime mover.
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…of specific fuel consumption (SFC) for an engine producing gas horsepower is 0.336 (pound per hour)/horsepower, or 0.207 (kg per hour)/kilowatt. In actual practice, the SFC is even higher than this lower limit because of inefficiencies, losses, and leakages in the individual components of the prime mover.
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