Compare calculators

Both calculators run independently — change the inputs on either side to compare results.

HVAC Load Calculator

Estimate the heating or cooling capacity (BTUs) your room needs based on size, ceiling height, insulation, and climate. Use this before sizing an air conditioner, heat pump, or furnace.

Room Area (sq ft)

Ceiling Height (ft)

Insulation Level

Climate Zone

Windows/Sun Exposure

Fill in the required fields to see your result.

Construction

Roof Area Calculator

Calculate the true sloped surface area of a roof from its footprint dimensions and pitch angle. The slope multiplier (1/cos(pitch)) corrects for the fact that a pitched roof has more material area than the horizontal footprint it covers.

Roof Length (m)

Roof Width (m)

Roof Pitch (degrees)

Fill in the required fields to see your result.

Key differences

	HVAC Load Calculator	Roof Area Calculator
Category	Construction	Construction
Inputs required	5	3
Result	Required BTU/Hour (BTU/hr)	Roof Surface Area (m²)
What it does	Estimate the heating or cooling capacity (BTUs) your room needs based on size, ceiling height, insulation, and climate. Use this before sizing an air conditioner, heat pump, or furnace.	Calculate the true sloped surface area of a roof from its footprint dimensions and pitch angle. The slope multiplier (1/cos(pitch)) corrects for the fact that a pitched roof has more material area than the horizontal footprint it covers.