Last updated: September 19, 2026
Estimates, not engineering documents
The calculators, articles, worksheets, and examples on Calculate HVAC Load are educational planning tools. They provide simplified estimates from the information you enter; they are not stamped engineering documents, permit-ready Manual J reports, or a substitute for a site inspection.
Verify before buying or installing equipment
A final HVAC design should be checked by a licensed HVAC contractor, mechanical engineer, or qualified energy professional who can inspect the building envelope, ductwork, electrical service, code requirements, and manufacturer performance data. Do not select, size, install, or modify equipment solely from a result on this site.
Inputs and real-world conditions
Results depend on the accuracy of your inputs and on assumptions about climate, insulation, windows, occupancy, infiltration, equipment efficiency, and operating conditions. Actual loads, comfort, energy use, costs, and savings can differ materially from the estimates shown.
Safety and compliance
HVAC, fuel-burning, refrigerant, electrical, combustion, and ductwork tasks can create serious safety risks. Follow local building, fuel-gas, electrical, refrigerant, and environmental rules, and use appropriately licensed professionals for work that requires certification or a permit.
No guarantee
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Questions and corrections
If you spot an error or need project-specific advice, please use our contact page.