Calculate Efficiency

Online calculator and formulas for calculating efficiency

Efficiency Calculator

Calculate efficiency

Calculates the efficiency (η) from input value and output value. The efficiency indicates how efficiently a machine or system operates.

W/J
Supplied energy or power
W/J
Useful output energy or power
Result
Efficiency:
Loss:

Example Calculation

Example: Electric Motor
Problem:

An electric motor consumes an electrical power of 1000 W and outputs a mechanical power of 850 W. What is the efficiency?

Given:
  • Input value P₁ = 1000 W (electrical power)
  • Output value P₂ = 850 W (mechanical power)
  • Find: Efficiency η
Solution:
\[\eta = \frac{P_2}{P_1} = \frac{\text{Useful power}}{\text{Input power}}\]
\[\eta = \frac{850 \text{ W}}{1000 \text{ W}} = 0.85\]
\[\eta = 0.85 = 85\%\]
Practical Applications
Electrical engineering: Motors, transformers, generators
Thermodynamics: Heat engines, cooling systems
Energy technology: Solar panels, wind turbines, power plants
Typical Efficiencies
  • Electric motor: 85-95%
  • LED lamp: 80-90%
  • Transformer: 95-99%
  • Combustion engine: 25-35%
  • Incandescent bulb: 5-10%
  • Solar cell: 15-22%

Formulas for efficiency

The symbol for efficiency is η (Greek letter eta). Efficiency is dimensionless and can be calculated with power or work.

Efficiency with power

Ratio of useful power to input power.

\[\displaystyle \eta = \frac{P_{\text{out}}}{P_{\text{in}}} = \frac{P_2}{P_1}\]
P₂ = output power, P₁ = input power
Efficiency with work

Ratio of useful work to input work.

\[\displaystyle \eta = \frac{W_{\text{useful}}}{W_{\text{input}}} = \frac{W_2}{W_1}\]
W₂ = useful work, W₁ = input work
Power loss

Calculation of non-usable energy.

\[\displaystyle P_{\text{loss}} = P_1 - P_2 = P_1 \cdot (1 - \eta)\]
Energy lost as heat, friction, etc.
Percentage representation

Conversion to percentage for better understanding.

\[\displaystyle \eta_{\%} = \eta \times 100\%\]
Efficiency of 0.85 equals 85%
Important Notes
  • Efficiency is always between 0 and 1 (0% to 100%)
  • An efficiency of 1 (100%) is theoretical and practically never achievable
  • The values must be given in the same unit
  • High efficiency = low energy loss = economical operation

Detailed description of efficiency

Definition and Significance

The effectiveness of a machine or system is called efficiency. Efficiency is dimensionless. This means there is no unit. It only indicates the relationship between effort and benefit, or input and output energy.

Usage Instructions

To calculate, enter the input value P1 and the output value P2. The values must be given in the same unit of measurement. Then click the 'Calculate' button.

Application Areas

Electrical Engineering

Electric motors, transformers, generators, power supplies. Evaluation of energy efficiency of electrical devices.

Thermodynamics

Heat engines, cooling systems, heating systems. Analysis of energy conversion processes.

Energy Technology

Solar panels, wind turbines, power plants, energy storage. Optimization of energy systems and installations.

Understanding Efficiency

Efficiency can have values between 0 and 1 and shows how efficiently energy is converted:

High efficiency (>80%)

Transformers: 95-99%
Electric motors: 85-95%
LED lamps: 80-90%

Medium efficiency (30-80%)

Combustion engines: 25-35%
Power plants: 30-50%
Solar cells: 15-22%

Low efficiency (<30%)

Incandescent bulbs: 5-10%
Steam engines: 8-12%
Old combustion engines: 15-25%

Conclusion: High efficiency means less energy loss and thus more economical and environmentally friendly operation!


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