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Energy Efficiency Calculator

Compare useful energy output against energy input to get efficiency and losses.

About Energy Efficiency Calculator

The efficiency is the share of total energy input that useful energy output represents, expressed as a percentage. The same figure is also shown per 1,000 and as a "one in every N" odds statement, which is easier to reason about when the rate is very small. Absolute counts hide scale — a rate normalises the number so you can compare periods, channels or cohorts of different sizes, where higher is better.

Formula

Energy Efficiency

Energy Efficiency = Useful energy output ÷ Total energy input × 100

Useful energy output
The subset being measured
Total energy input
The full population it is drawn from

Worked example

With the default values below, Energy Efficiency Calculator returns Energy Efficiency of 78.00%. Change any input above and every figure here is recalculated in your browser.

Inputs used

Useful energy outputminimum 0
780
Total energy inputminimum 0
1,000

Results

Energy Efficiency
78.00%
Remaining (whole minus part)
220
Equivalent per 1,000
780.0
One in Every
1.3

Step by step

  1. 1Values used
  2. 2Energy Efficiency
  3. 3Energy Efficiency= 78.00
  4. 4Remaining (whole minus part)= 220
  5. 5Equivalent per 1,000= 780.0
  6. 6One in Every= 1.3

Assumptions and limits

  • The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is Energy Efficiency calculated?

Energy Efficiency = Useful energy output ÷ Total energy input × 100 The efficiency is the share of total energy input that useful energy output represents, expressed as a percentage. The same figure is also shown per 1,000 and as a "one in every N" odds statement, which is easier to reason about when the rate is very small.

Why does Energy Efficiency matter?

Absolute counts hide scale — a rate normalises the number so you can compare periods, channels or cohorts of different sizes, where higher is better.

What values do I need to enter?

This calculator takes 2 inputs: Useful energy output, Total energy input. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

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