Simplified Manual-J style estimate; get a full Manual J for final equipment sizing.
Example: Conditioned area: 1,800 sq ft · Climate: Moderate · Insulation: Average · Occupants: 4 → Cooling load: 52,000 BTU/hr.
In tons: 4.3 tons
Suggested unit size: 4.5 tons
Frequently asked questions
How do I calculate hvac load? Simplified Manual-J style estimate; get a full Manual J for final equipment sizing. Enter your numbers above and the result updates instantly. For example: Conditioned area: 1,800 sq ft · Climate: Moderate · Insulation: Average · Occupants: 4 → Cooling load: 52,000 BTU/hr.
Is this HVAC Load Calculator free? Yes — completely free with no sign-up or paywall. It runs entirely in your browser and keeps working offline; the numbers you enter never leave your device.
How accurate is it? It uses the standard published formula for hvac load. Results are estimates for planning — not financial, tax, medical, engineering, or legal advice.