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BTU Heating & Cooling Calculator

BTU/hr needed to heat or cool a room.

Estimate the BTU/hr capacity needed to heat or cool a room from its area and a climate-zone factor (10–60 BTU/ft² for heating, 18–35 BTU/ft² for cooling, depending on insulation and sun exposure).

Nadia Almasri By Nadia Almasri
Published Last reviewed 1 min read

Inputs

ft²
ft
BTU/ft²

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

BTU/hr = room area × BTU per ft² factor × ceiling adjustment.

In depth

Estimate the BTU/hr capacity needed to heat or cool a room from its area and a climate-zone factor (10–60 BTU/ft² for heating, 18–35 BTU/ft² for cooling, depending on insulation and sun exposure).