Boiler Efficiency Calculator

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The Simplest Way to Check Boiler Performance

The direct method compares useful heat output against total fuel energy input, giving a quick overall efficiency figure without needing a detailed breakdown of individual losses.

The Formula

Boiler Efficiency % = (Heat Output / Fuel Input) × 100

Worked Example

A boiler producing 246 kW of steam heat from 300 kW of fuel input:

Efficiency = (246 / 300) × 100 = 82%

How to Use This Calculator

  1. Enter the Heat Output delivered to steam or hot water.
  2. Enter the total Fuel Input energy.
  3. Select Calculate to get boiler efficiency.

Related Calculations

Need the flue-gas-based estimate instead? See the Combustion Efficiency Calculator, or check fuel required for a target output in the Boiler Fuel Requirement Calculator.