Boiler Efficiency
Use the Boiler Efficiency for hvac planning. Enter Useful heat output and Fuel heat input to get a clear result, formula explanation, and practical checks.
Boiler Efficiency measurements
Enter your values, then calculate.
Result
How to calculate boiler efficiency
This calculator finds boiler efficiency as a ratio of two energy measurements — typically useful heat output against total fuel energy input.
How the calculation works
Efficiency = Output value ÷ Input value (often expressed as a percentage by multiplying by 100). This shows what fraction of input energy is converted to useful output.
Example
A boiler producing 85,000 BTU of useful heat from 100,000 BTU of fuel input: Efficiency = 85,000 ÷ 100,000 = 0.85, or 85%.
Frequently asked questions
How is Result calculated?
Result = [Useful heat output] ÷ [Fuel heat input] × 100.
Is the Boiler Efficiency free to use?
Yes — every calculator on Simple Calculator Tools is free, runs in your browser, and does not require an account.
Boiler Efficiency
Efficiency = Output value ÷ Input value (often expressed as a percentage by multiplying by 100). This shows what fraction of input energy is converted to useful output.
Let's understand your boiler efficiency result.
Calculate a result above and this guide will help you interpret it using this calculator's own formula and explanation.
Pro Tips for Boiler Efficiency
- Combustion (steady-state) efficiency and seasonal/annual fuel utilization efficiency (AFUE) are different measurements — confirm which one your inputs represent.
- Boiler efficiency typically degrades over time without maintenance; periodic re-measurement helps catch that decline.
Common Boiler Efficiency Mistakes to Avoid
- Confusing combustion efficiency (a snapshot measurement) with AFUE (an annualized, real-world average that accounts for cycling losses) — these numbers are not interchangeable.
When to Use This Calculator
This calculator finds boiler efficiency as a ratio of two energy measurements — typically useful heat output against total fuel energy input.