Energy Efficiency Calculator

Calculate input energy, useful output energy, and a load-based energy efficiency ratio for equipment or appliances.

883.8K uses Updated · 2026-05-25 Runs locally · zero upload
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How to Use Energy Efficiency Calculator

  1. Enter device power in watts. Use rated power for planning or measured power for a more realistic estimate.
  2. Enter use time in hours for the period you want to analyze.
  3. Enter load factor from 0 to 1, where 1 means full useful load and lower values mean less useful output.
  4. Calculate to see total input energy in kWh, useful energy, unused share, and the efficiency ratio.

Formula & Theory - Energy Efficiency Calculator

Input energy (kWh) = power (W) x hours / 1000
Useful output energy = input energy x load factor
EER = useful output energy / input energy
  • The visual bar shows how much of the consumed energy is treated as useful output under the selected load.

Use Cases for Energy Efficiency Calculator

  • Estimating appliance electricity use before choosing run time.
  • Comparing equipment behavior under light load and full load.
  • Explaining why high power with low useful load can waste energy.

Frequently asked questions about Energy Efficiency Calculator

What inputs does Energy Efficiency Calculator need?

Enter device power in watts. Use rated power for planning or measured power for a more realistic estimate.

How should I interpret the result?

The visual bar shows how much of the consumed energy is treated as useful output under the selected load.

Is my data stored?

No. All calculations happen in your browser; nothing is sent to a server.