Efficiency may refer to:

• Energy efficiency, useful work per quantity of energy
  • Energy conservation, reducing the use of energy
  • Electrical efficiency, useful power output per electrical power consumed
  • Fuel efficiency, converting energy in fuel to kinetic energy or work
    • Specific impulse, in propulsion systems, a measure of fuel-efficiency
  • Volumetric efficiency, in internal combustion engine design
  • Lighting efficiency, visible light from a light source per unit of energy, in lumens per watt
  • Mechanical efficiency, the effectiveness of a simple machine, mechanical advantage over ideal mechanical advantage
  • Thermodynamic efficiency, useful work per change in heat
    • Exergy efficiency, measure of 2nd-law themodynamic loss
    • Thermal efficiency, useful work per the higher heating value of the fuel
• Efficiency (economics), a general term, to capture the amount of waste or other undesirable features
  • Pareto efficiency, making one individual better off, without making any other individual worse off
  • Kaldor-Hicks efficiency, like a less stringent Pareto efficiency
  • Allocative efficiency, an optimal distribution of goods
  • The optimisation of a social welfare function
  • Efficiency wages, paying workers more than the market rate for increased productivity
• Efficiency (statistics), a measure of desirability of an estimator
• Efficiency ratio, expenses as a percentage of revenue, etc.
• Efficiency Movement, of the Progressive Era 1890-1932, advocated efficiency in the economy, society and government
• Material efficiency, compares material requirements between construction projects or physical processes
• Textual efficiency, density of a message
• Algorithmic efficiency, the speed and space requirements of a computer program
• Quantum efficiency
• A one room apartment

Effizienz | Eficiencia | נצילות | Efficienza | Izkoristek