Heat Loss (Simplified) Calculator

Estimate required heating output using floor area and a heat loss factor.

Calculator

Building Condition

Heat Loss Factor (BTU/hr per ft²)

Floor area (ft²)

Total Heat Loss

0 BTU/hr

Enter values above and click calculate.

How It Works

This calculator estimates the heating output required for a space using floor area and a heat loss factor. It is a simplified rule-of-thumb method commonly used for quick estimates during the quoting and planning stages — before a full Manual J load calculation is performed.

Heat Loss (BTU/hr) = Floor Area (ft²) × Heat Loss Factor

Where:
Floor Area (ft²) = the conditioned floor area of the space in square feet
Heat Loss Factor = estimated heat loss per square foot in BTU/hr — varies based on insulation, construction quality, and climate
Result = total estimated heating output required in BTU/hr

Typical heat loss factors by building condition:
Well insulated modern home: 20–25 BTU/hr per ft²
Average residential construction: 30–35 BTU/hr per ft²
Older poorly insulated home: 40–50 BTU/hr per ft²
Cold climate/Alberta winter — add 5–10 BTU/hr per ft² to your estimate

Common example: A 1,000 ft² average home at 30 BTU/hr per ft² requires approximately 30,000 BTU/hr of heating output.