Home & Construction
HVAC BTU Calculator - Calculate required BTU for heating/cooling your space
Calculate required BTU for heating/cooling your space
Formulas and edge cases are reviewed against authoritative references before publication. For methodology, editorial standards, or corrections, use the links below.
Frequently asked questions
What is BTU?
British Thermal Unit measures heating/cooling capacity. Higher BTU = more powerful unit.
How many BTU per square foot?
Generally 20-25 BTU per sq ft, but varies by climate, insulation, and sun exposure.
What if I get wrong size?
Undersized won't cool/heat effectively. Oversized cycles too often, wasting energy and causing humidity issues.
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About this tool
This HVAC BTU Calculator turns your inputs into practical results. Provide Ceiling Height, Average, and Extra large unit to calculate AC Tonnage and Required BTU.
Adjust values to compare scenarios and see how sensitive the result is. The calculation uses the numbers as entered, so double-check units and expect small differences from rounding in the displayed totals.