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About this calculator

Use the HVAC BTU Sizing to get 2 linked results (Typical 20 BTU/ft2, Cold climate 30 BTU/ft2) from a single number. It is built for home & construction jobs where a quick, repeatable answer beats guesswork. Room size is only one factor; ceiling height, windows and insulation change real heating loads.

How it works

The calculator multiplies your input by a fixed coefficient for each line. For example, every 1 m2 gives 215.3 BTU/h for typical 20 btu/ft2.

Worked example

If you enter 30 (Room area (m2)), Typical 20 BTU/ft2 comes to 6,459 BTU/h and Cold climate 30 BTU/ft2 comes to 9,687 BTU/h.

Common mistakes

• Room size is only one factor; ceiling height, windows and insulation change real heating loads.
• Skipping the check against local building code or manufacturer data.

FAQ

How much typical 20 btu/ft2 do I need per m2?

Each 1 m2 gives 215.3 BTU/h.

How is Cold climate 30 BTU/ft2 calculated?

Cold climate 30 BTU/ft2 equals your input times 322.9 BTU/h. With 30 entered, that is 9,687 BTU/h.

Are the results exact?

Results are precise sums of the stored coefficients, but real-world typical 20 btu/ft2 varies, so keep a safety margin. This is general information, not professional advice.

What is the most common mistake?

Room size is only one factor; ceiling height, windows and insulation change real heating loads.

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