Furnace Output Capacity
Use the Furnace Output Capacity. Enter Input capacity (BTU/hr) and Efficiency (%) for a clear result, formula explanation, and practical planning checks.
Furnace Output Capacity measurements
Enter your values, then calculate.
Result
How to calculate furnace output capacity
This calculator finds furnace output capacity by multiplying input capacity by efficiency — output is always less than input due to combustion and heat-transfer losses.
How the calculation works
Output capacity = Input capacity × (Efficiency ÷ 100).
Example
A furnace with 100,000 BTU/hr input capacity at 95% AFUE efficiency: Output capacity = 100,000 × 0.95 = 95,000 BTU/hr.
Frequently asked questions
How is Result calculated?
Result = [Input capacity] × ([Efficiency] ÷ 100).
Is the Furnace Output Capacity free to use?
Yes — every calculator on Simple Calculator Tools is free, runs in your browser, and does not require an account.
Furnace Output Capacity
Output capacity = Input capacity × (Efficiency ÷ 100).
Let's understand your furnace output capacity result.
Calculate a result above and this guide will help you interpret it using this calculator's own formula and explanation.
Pro Tips for Furnace Output Capacity
- Furnace sizing decisions should be based on output capacity (what actually heats your home), not input capacity (what the furnace burns).
- Higher-efficiency furnaces deliver more usable heat per unit of fuel burned, which is the basis for their typically higher purchase cost being offset over time by fuel savings.
Common Furnace Output Capacity Mistakes to Avoid
- Sizing a home's heating needs against a furnace's input rating instead of its output rating, which overstates actual delivered heating capacity.
When to Use This Calculator
This calculator finds furnace output capacity by multiplying input capacity by efficiency — output is always less than input due to combustion and heat-transfer losses.