Efficiency Calculator

In physics, efficiency is a dimensionless metric that measures the performance of a device or process relative to energy conservation. Because energy cannot be created or destroyed, the total energy put into a system must equal the total energy coming out, which includes both useful output and wasted energy (such as thermal dissipation or friction). The standard mathematical formula for efficiency (η) is expressed as: η = (Output / Input) × 100%. Alternatively, when expressed as a decimal fraction, it is simply Output divided by Input.

Imagine an industrial electric motor designed to lift heavy freight. You supply an electrical input energy of 2,500 Joules into the motor. Through internal mechanical work and friction, the motor successfully delivers 1,875 Joules of useful kinetic energy to lift the freight. To find the efficiency, divide the useful output energy (1,875 J) by the total input energy (2,500 J), which yields 0.75. Multiply this decimal by 100 to get a final efficiency of 75%. This means 75% of the electrical energy was successfully converted into lifting work, while the remaining 25% was lost primarily as heat and sound.

Always ensure that your input and output variables are measured in identical units before performing any manual calculations. For instance, if your input is measured in Joules per second (Watts), your output must also be in Watts. Additionally, remember that real-world friction and air resistance mean that outputs can never exceed inputs; if your calculated efficiency is greater than 100%, check your variables for inverted data.