What it calculates
Estimate a basic heating/cooling load from room area and adjustments.
BTU / Room Sizing Planner
Estimate a basic room heating/cooling load using floor area and adjustment factors.
Planning and estimating aid only. Verify project requirements, manufacturer instructions, adopted codes, permits, and field conditions before performing regulated work.
HVAC planning
How to Use This Calculator
Use the field units shown below, then compare your result with the worked example. Do not buy equipment from this number alone.
How the calculation works
Floor area is multiplied by the entered BTU-per-square-foot basis and the selected insulation/exposure adjustment.
What the result means
It is a quick planning estimate, not a formal heating or cooling load calculation.
Separate a rule-of-thumb load from equipment selection
With 200 square feet, an entered planning factor of 20 BTU/hr per square foot and an insulation multiplier of 1, the model returns 4,000 BTU/hr. Dividing by 12,000 gives about 0.33 nominal tons of equivalent capacity.
Contractor tip: Do not buy equipment from this number alone. Use a proper load calculation and equipment-selection process; a larger unit is not automatically the better match.
Verify the final quantity
The factor and insulation multiplier are user assumptions. This floor-area model does not calculate heat gain through each surface, weather design conditions, infiltration, shading or latent load.
Good practice: Compare the calculated quantity with plans, specifications, product packaging and current field conditions before purchasing material.
Further reading: Department of Energy: proper sizing of HVAC systems.