HVAC Load & Duct Sizing Calculator

Simplified Manual J — room-by-room BTU/hr, equipment tonnage, CFM, and duct schedule in seconds.

◆ Project Settings
ASHRAE 169 climate zone for design temps
Server room, commercial kitchen equipment, etc.
◆ Room Schedule
◆ Summary
Room & Duct Schedule
Room Sq Ft Cooling BTU Heating BTU CFM Round Duct Rect. Duct
AI-Generated Report
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Quick Reference

Rule of thumb: 25–35 BTU/sq ft for well-insulated residential. HVAC calculators above 40 BTU/sq ft — check your envelope.

Duct friction rate: Target 0.08–0.10 in. wc/100 ft for balanced airflow. Oversize trunks, rightsize branches.

Sizing note: This tool uses simplified Manual J. For permit-required calcs, use ACCA-certified software or a licensed engineer.

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