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HVAC made simple
HVAC CALCULATOR
AFUE Efficiency Calculator
Compare furnace efficiency, estimate useful heat output, energy loss, and potential annual fuel savings.
1. Current Furnace
Enter the AFUE rating of your existing furnace.
%
BTU/hr
2. Replacement Furnace
Enter the AFUE rating of the furnace you are considering.
%
$
/year
3. Optional Upgrade Cost
Enter the estimated upgrade cost if you also want to calculate a simple payback period.
$
YOUR RESULTS
AFUE Efficiency Comparison
Current Furnace
80%
AFUE
→
New Furnace
96%
AFUE
Efficiency Improvement
20.0%
Current Useful Heat Output
0 BTU/hr
Current Heat Loss
0 BTU/hr
New Furnace Useful Heat Output
0 BTU/hr
New Furnace Heat Loss
0 BTU/hr
Estimated Annual Fuel Savings
$
0
/ year
Efficiency Breakdown
Current Furnace Fuel Used for Heat
0%
Current Furnace Energy Lost
0%
New Furnace Fuel Used for Heat
0%
New Furnace Energy Lost
0%
Estimated New Annual Fuel Cost
$0
Estimated 10-Year Fuel Savings
$0
Simple Payback Period
—
What Does AFUE Mean?
AFUE stands for Annual Fuel Utilization Efficiency. It represents the percentage of fuel energy that a furnace converts into usable heat over a typical heating season.
For example, an 80% AFUE furnace converts approximately 80% of its fuel energy into usable heat, while approximately 20% is lost through combustion and exhaust.
Important:
Estimated savings assume the home requires the same amount
of useful heat before and after the furnace upgrade.
Actual energy costs can vary based on weather, thermostat
settings, equipment sizing, duct losses, fuel rates,
maintenance, and household usage.