Efficiency Calculator

Calculate the efficiency of a system. Enter the total energy input in to a system, and the total energy or work output to determine it’s efficiency.

Efficiency is the avoidance of waste in any system, often displayed as a percentage of work output to energy input. This energy is usually measure in Joules (J). Efficiency is very often used in applications of heat transfer, since heat loss is a core issue in modern day engineering. It’s also used to evaluate mechanical, solar, and chemical efficiencies.

Efficiency Formula

Efficiency can be calculated through the following formula:

N = Wo / Ei * 100

  • Where N is efficiency
  • Wo is work output
  • Ei is energy input

Work and energy both use the standard unit of Joules, but the calculator above is unit less to allow you to input any unit. You need to make sure the units of work and energy match. The above explanation is for the use of efficiency in physics and thermodynamics, but efficiency can be used in anything from finance to work performance.

efficiency calculator

How to Calculate Efficiency

Efficiency is a measure of a systems ability to transfer energy. So a system with a 100% efficiency will output 100% of the energy input. If you have study thermodynamics of course, you know that 10)% efficiency is impossible. There is energy loss in every single aspect of a system, from heat loss to friction loss.

Let’s take a look at an example of how you can calculate efficiency.

  1. The first step is to calculate or measure the energy being input into a system. This is generally measured through direct means, like measuring the total electricity input into a system, but it can also be calculate.
  2. The next step is to calculate the total work output. This can sometimes be tricky and require some manipulation of equations. The reason this can be hard is because very often, an input it either electricity or heat, and the output is motion, like that of a motor. You must convert physical motion into energy using thermodynamic formulas
  3. Last, enter the input and output into the formula and analyze the result.

How to improve Efficiency

Improving efficiency is the back bone of continuous improvement in engineering, especially in mechanical systems. Mechanical systems can be extremely inefficient. Take for example the ICE (internal combustion engine). The ICE usually averages around a 20-30% efficiency. That means, that 70% of the energy provided by the gasoline is lost for various reasons. Engineers have been working to improve this for decades.

Here are the best ways to improve the efficiency of mechanical systems:

  • Reduce heat loss through use of insulation
  • Reduce friction of parts through lubrication or redesigning components
  • Reduce the number transfer components, the less the better
  • Capture lost heat to power other systems

There are an unlimited number of ways someone can improve the efficiency of a system, mechanical or not. It’s up to an engineer to critically think and come up with new ways to do that.

If you’re interested in learning more about science and engineering, visit our calculators here.


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