Heat Load Calculator
Calculate heating and cooling loads for accurate HVAC sizing
Why this tool matters
Sizing decisions should not live in disposable notes. Use this estimate now, then keep the result with the installed-base record so future service, warranty, and replacement decisions start with better context.
Next best step
Start free when you want load assumptions, equipment details, and follow-up timing tied together in one workflow.
💡 Load Breakdown
⚠️ Important Notes
- • This is a simplified heat load calculation. Professional Manual J calculations account for more variables.
- • Always consult manufacturer specifications and local codes.
- • Consider duct losses (typically 15-25%) when sizing equipment.
- • Oversizing can lead to short cycling and poor humidity control.
What is Heat Load Calculation?
Heat load calculation (Manual J) is the industry-standard method for determining the correct HVAC system size. It accounts for building construction, insulation, windows, climate, and occupancy to calculate heating and cooling requirements.
Key factors:
- • Sensible Heat: Heat that changes temperature (walls, roof, windows)
- • Latent Heat: Heat that changes humidity (occupants, cooking, moisture)
- • Infiltration: Air leakage through cracks and openings
- • Ventilation: Fresh air requirements for occupants
Proper sizing prevents oversized equipment, reduces energy costs, and improves comfort and humidity control.