BTU Calculator
⚙️ Input Values
📊 Result
📋 Calculation History
📖 About the BTU Calculator
BTU (British Thermal Unit) is the standard measurement for heating and cooling capacity. Proper sizing of HVAC equipment is crucial — an undersized unit runs constantly without reaching the target temperature, while an oversized unit short-cycles, wasting energy and causing humidity problems.
The basic rule of thumb is 20 BTU per square foot, but this varies significantly based on ceiling height, insulation quality, climate zone, window area, and sun exposure. Our BTU calculator applies industry-standard multipliers from ASHRAE guidelines to give you an accurate estimate.
For cooling, 12,000 BTU equals 1 ton of air conditioning. A typical 1,500 sq ft home in a moderate climate needs approximately 2.5 tons (30,000 BTU). Always consult a licensed HVAC professional for final equipment selection.